Owener Spec for Piping

PT Tenaga Listrik Cilegon 170MW (equiv) Combined Heat & Power Plant Project, Banten, Indonesia Tender Documents Section 3 – Employer’s Requirements Page 165

Pöyry Energy Ltd. Sect3_ITB

17 PIPING SYSTEM

17.1 General Requirements The piping shall be engineered, procured and constructed considering the full range of design pressures and temperatures, the full range of site ambient conditions and the service medium characteristics. This requirement is also applicable for all temporary pipework to be installed to assist plant cleaning and commissioning.

The piping systems shall conform to the codes and standards specified in the various sections of this specification. ASME B 31.1 shall be the standard applied for the main power island process piping, including the boiler integral pipework. The codes and standards shall be of the latest edition including all revisions, supplements, and addenda which are in effect as of the date of issuance of the specification and shall be considered to be part of this specification. The use of other internationally recognized codes and standards are subject to the Employer’s approval. If the agreed codes and standards are published in any language other than English translations into English shall be provided for all documents required by the Employer for design review.

All parts and works necessary for the safe and efficient operation of the piping shall be provided down to the smallest detail even if they were not particularly mentioned in the specification.

17.1.1 Codes and Standards All works, equipment, materials and systems shall be designed, manufactured and/or constructed in accordance with the latest issue of the relevant international codes and standards.

17.2 Design Requirements

17.2.1 General The Bidder shall design all piping systems in accordance with applicable system performance and operating data and shall be responsible for all dimensions, wall thickness, pressure losses, stress calculations, and reliability of the systems. The piping systems shall be designed to meet the requirements of trouble-free and safe operation under maximum load, part load, transient and fault conditions. All parts and works necessary for the safe and efficient operation of the piping shall be provided down to the smallest detail even if they were not particularly mentioned in the specification.

The Bidder shall confirm in his proposal that the applicable design code for the following systems is ASME B31.1:

• Steam Pipework (main steam, cold reheat, hot reheat and process steam) including vents and drains.

• Steam Turbine bypass system.

• Steam turbine integral pipework, extraction steam lines, gland steam line, vents and drains.

• Feed water pipework including vents and drains.

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• Feed water ancilliary pipework (e.g feed pump minimum flow lines, attemporator spray pipework).

• Condensate system including vents and drains.

• Feed heating system integral pipework.

• Turbine control oil pipework.

• Fuel oil pipework.

• Turbine lubricating oil pipework.

• Compressed air pipework. Piping materials for the above systems shall be selected from seamless material listed in the chosen international design standards. Equivalent materials shall not be used.

Piping systems which are exposed to creep shall be fitted with creep pips or other means to allow periodic measurement of diametral creep distension.

Double isolation shall be provided for all piping systems with a design pressure of 40 bar(g) or above. This requirement is applicable for any equipment that requires isolation for on-line maintenance and for all drains, vents and instrument root valves.

Drain and vent lines after the second isolating valve for the boiler, feedwater pipework, steam pipework and the steam turbine shall have a wall thickness equal to schedule 80.

All pipe fittings shall be proprietary fittings. All small bore connections to pipe systems shall be by weldolets, sockolets or threadolets or similar proprietary fittings.

During the design phase the Contractor shall submit General Arrangement drawings for all piping systems, including drains and warming lines, covered in this Section of the specification for approval. General Arrangement drawings shall indicate all lines DN80 and above in full detail. Lines below DN 80 shall be indicated by centre line only. From the general arrangement drawings the Contractor shall develop detail drawings, piping isometric drawings and pipe spool drawings for pipework erection.

Pipework below DN 50 may be installed as site run pipework for cold water systems, compressed air distribution system, and system drains and vents. However the site running of steam line drains is not permitted.

Pipework shall not be run across floors or walkways or anywhere that would constitute a safety hazard, trip hazard or an obstruction for plant maintenance.

17.2.2 Design Pressure The design pressure of a piping system subject to internal pressure is defined as the highest of the following:

• The requirements of the selected design code

• Design pressure of the equipment to which the piping is connected

• Set pressure of a relief valve of the piping or equipment system

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• Pressure not lower than the shut-off pressure resulting from the sum of the maximum suction pressure plus 1.5 times the design differential pressure, for discharge lines of centrifugal pumps not protected by a relief valve

• Pressure corresponding to absolute vacuum for piping systems under vacuum pressure. All steam lines shall be designed for full vacuum or properly safeguarded.

• Lines for liquids, which may have vacuum, shall be designed for vacuum or properly safeguarded

The design pressure as defined above shall be assumed in the design of the whole piping beginning from the operating machine (or equipment) upstream up to the last valve (included) located before the inlet into the equipment with a lower design pressure.

In the systems including control valve by-pass sets, the isolating valves and the by-pass valve shall always be provided for the design pressure upstream.

17.2.3 Design Temperature The design temperature of a fluid in a piping system is the maximum temperature expected for the fluid from the equipment, machine or fluid supply. The design temperature shall consider limitations of control systems (e.g. the control range for boiler steam temperature), radiant heat gain and thermal conduction.

If exact data on maximum fluid temperature cannot be established the normal operating temperature plus 20-30 deg. C shall be used.

The design temperature of the piping material is the same as that of the fluid.

The operating temperature, thus defined, can be used for the purpose of determining the insulation thickness and the design temperature for thermal stress analysis and flexibility of the piping.

The use of carbon steel shall be restricted to pipe systems with a design temperature below 425ºC.

17.2.4 Pipe System Velocities Unless stated elsewhere within this specification fluid velocities shall not exceed the values stated between

Fluid Velocity m/sec Saturated steam 20 - 30

Superheated steam 30 - 45

Superheated steam (300 mm and larger pipe size) 50 – 60

Steam exhaust to atmosphere 25 - 50

Reheat steam 30 – 40

Turbine LP Bypass after PRV 50 - 75

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Main cooling water pump suction 1.0 – 1.5

Main cooling water pump discharge lines 2.0 – 2.5

Pump inlet for water 2.0 – 2.5

Pump outlet for water less than 10 bar 2.5 – 3.0

Pump outlet for water 10 bar or more 3.0 – 3.5

Drains 1.0 – 2.0

Low pressure air (less than 10 bar) 20 – 30

High pressure air (10 bar or more) 10 – 15

Fluid Velocity m/sec Air compressor inlet 10 – 20

Fuel oil and lubrication oil 0.5 – 2.0

17.2.5 Piping Arrangement Design – General Requirements The piping layout and arrangement shall be clearly shown on flow diagrams, pipe routing, isometric and erection drawings. Pipe dimensions, materials, operating conditions, insulation thickness, and piping and equipment identification numbers shall be shown on the relevant drawings.

The Bidder shall design all piping systems with the piping arranged in orderly pipe runs giving due consideration to pipe expansion, valve locations, practical pipe supporting, and access to all piping accessories for maintenance purposes.

No nozzle or branch weld shall encroach over the heat affected zone of main pipe butt welds.

Piping arrangements shall provide for the removal and/or maintenance of equipment and equipment internals without removing the piping. A minimum of 2.1 metre headroom shall be maintained to the bottom of all piping components or insulation in walking areas.

A minimum passageway of 1 metre shall be provided for access between and around all equipment, and a 50 mm minimum clearance shall be provided between piping, including insulation, and any point of adjacent equipment of piping. Additional clearance shall be provided, where required, for pipe movement due to thermal expansion.

In developing the general arrangement drawings, particular attention shall be given to access and egress throughout the plant:

• Pipes shall be routed so that clearances around the pipe are adequate to meet installation and field welding requirements, and furthermore valve, instrument, and support maintenance requirements

• Pipes shall be routed to reserve space for cable trays between the bottom of the floor steel and the top of the pipe (or the top of the pipe insulation) taking into account the worst condition, either hot or cold

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• Interference with pipe supports shall be prevented.

• Contractor shall co-ordinate the design of all piping systems with other power plant services (e.g. cabling) to ensure that there is no interference.

• Adequate clearance shall be provided around all pipes to permit the installation of insulation material. Local reduction of insulation thickness due to interference with other pipework equipment or structures will not be permitted.

• The general clearances for crossings and passageways defined in Chapter 3.7.1 shall also apply.

In general, the branches shall be located at the bottom or at the side of lines conveying liquids, and at the top of lines conveying gases or vapours. Branches shall be furnished with an isolating valve close to the branching point.

Pipes shall be arranged in such a manner that thermal expansion does not cause any undue stresses on the piping. The same requirement applies to vent and drain pipes.

Piping shall be supported so as to minimise the loads on pump and equipment nozzles.

Piping for connection to equipment shall be installed so as to leave a sufficient clearance for access and maintenance operations.

All condensate and water lines shall be run with a minimum gradient of 1:500 sloping downwards in direction of flow.

Pump suction pipes shall be routed in such a manner that no air can be trapped in the suction piping. The top of the suction branch lines shall be in no place lower than the top of the manifold at the point of their interconnection.

17.2.6 Valve Arrangements All manual isolating valves shall be manoeuvrable, in order of precedence, in the following manners:

• from grade

• from walkway or from a special platform

• by extension

• by chain The height of hand wheel axis from the operating floor shall preferably be 1,200 or 1,400 mm; in any case, it shall not exceed 1,800 mm.

Normally, the valves shall not be installed with the stem below the horizontal position.

All valves with one end non-connected shall be equipped with blind flanges or plug.

17.2.6.1 Safety and/or Relief Valve Arrangements These shall be located as close as possible to the equipment they are to protect, and be accessible for inspection and maintenance purposes.

Relief or safety valve venting to atmosphere shall be arranged as follows:

• steam vent pipes shall be routed to free atmosphere outside the building. Preferably the vent pipes shall be separate for each valve.

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• condensate and water vent pipes shall be routed to the nearest trench on ground floor. Special attention shall be paid to flashing fluids. Vent pipes shall be arranged and dimensioned also for the flashing.

Preferably each valve shall be oriented to discharge parallel to the axial centre-line of the pipe it is protecting.

Each pipe discharging to atmosphere shall have a 1/2" (min.) diameter drain pipe at the lowest point.

Relief valves shall always be installed on those lines which may be closed off at both ends, if the line internal fluid, at maximum ambient temperature, may reach a pressure higher than the rating of the line itself.

17.2.6.2 Vents and Drains All pipelines shall be provided with vent and drain connections at all high and low points respectively, and also as otherwise required for suitable operation.

Where practicable, all steam lines shall be sloped in the direction of steam flow and shall be adequately trapped at low points and vented at high points in the pipe runs. Drip legs shall be provided on steam lines at the drainage points to avoid blockage of drain pipes. Each trap and strainer arrangement shall have suitable block valves, bypass valve, strainer, and blow-off valve.

High pressure and high temperature drain lines shall have a slope of 2.5% for drainage to ensure that a slope is maintained during the life of the plant when allowance is made for possible pipe creep, pipe settlement and spring hysteresis.

The position of isolating valves and orifices shall be taken into account, when locating drip legs. Condensate pots, drip legs and drain lines shall be adequately sized to remove all condensate during plant start-up. Each drainage pipe shall be separately run to blow-down vessels, drain tanks or flash vessels as may be appropriate.

Piping for drains and vents from vessels shall be protected from erosion/corrosion by the same material as the vessel lining unless otherwise approved by the Employer.

All system piping shall be arranged to permit complete drainage when the plant is shutdown.

All vent lines shall be terminated 3 m or higher above the highest service platform.

All drain lines, which run to waste, shall be routed to a suitable drain trench, floor drain, or sewer.

The sizes of vent and drain valves shall be selected as a function of the characteristics of the fluid to be vented or drained however they shall not be smaller than the following:

• Lines DN 50 and smaller: size of vent DN 15 and drain size DN 25

• Lines DN 65 ... DN 250: size of vent DN 20 and size of drain DN 40

• Lines DN 300 and larger: size of vent DN 25 and size of drain DN 50

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17.2.7 Stress Analysis

17.2.7.1 General Stresses due to thermal expansion and mechanical loads in the piping systems and in the selection of the type of supports shall be checked. The stress and flexibility analysis shall be calculated using proprietary computer software specifically that is compatible with the piping design code.

As a minimum requirement the following pipe systems shall be checked and stress analysed:

• all high pressure steam systems including drains and safety valves

• all high pressure feed water excluding small sized lines ( DN 50)

• all steam lines connected to the turbines including heater connections Generally, high pressure is considered to be a design pressure of 40 bar(g) or above. The specified requirements represent the minimum requirements, and the Contractor shall perform stress analysis of other systems that may potentially be subject to significant thermal stresses and/or expansion based on the Contractor’s design considerations and practices.

In general it is recommended to avoid, as far as possible, the use of expansion joints and cold pull.

Each piping system shall be considered as a structure properly supported, which works at the operating conditions stated in the specifications for the respective equipment. If the flexibility of the pipe is insufficient, the expansion shall be absorbed adopting the procedures below in the listed order of precedence:

• spring or constant supports

• guides or restraints

• change in piping routing

• insertion of loops built from pipe and bends

• installation of expansion joints

17.2.7.2 Accuracy of Calculations The calculation methods applied shall have an accuracy degree proportioned to the importance of the piping and the operating conditions. The Contractor shall submit calculation sheets for all required piping systems for the Employer's approval.

17.2.7.3 Adjusting Temperature for Stress Analysis Calculations The following requirements shall apply:

• the turbine exhaust piping shall be checked also at full speed no load temperature

• the steam turbine bleed-off piping shall be checked also at the highest possible temperature

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• the exhaust pipes after attemperator stations shall be checked also in a case in which the supply of spray water is lost.

For circuits with one normal operating temperature and a second different temperature for transitory periods, both conditions shall be analysed.

17.2.7.4 Lines Temporarily Closed For lines connected to two or more items of equipment, of which one is operating and the remaining ones are still-standing, the temperature established in the dead sections shall be analysed and considered in the flexibility analysis.

17.2.7.5 Stresses on Equipment The stresses produced by piping (due to weight, expansion forces, etc.) on pumps, vessel shells and heads of vessels, shall be checked for being limited within the allowable values accepted by the equipment manufacturer. The Contractor shall submit a schedule of permissible nozzle loadings for the boiler connections, turbine connections, condenser connections, feed heater connections and boiler feed pump connections. The data for the schedule shall be provided by the equipment manufacturers.

17.2.8 Pipe Supports and Hangers High pressure pipe supports shall be designed and spaced in accordance with the requirements of the pipework design code and the results of the pipework stress analysis report.

All hangers and supports for high pressure piping systems shall be proprietary items capable of meeting the requirements specified by the pipework stress and flexibility report. The Bidder shall nominate a short list of proposed suppliers of pipe supports and hangers in his Proposal.

During the Design Phase the Contractor shall submit details of all proposed pipe supports and hangers to the Employer for approval. Each pipe hanger or support shall have its own unique number and shall be identified on the relevant isometric drawings and shall be cross referenced with pipe hanger design documents.

17.2.9 Miscellaneous Design Requirement

17.2.9.1 Fire Water System The fire water pipework shall be installed above ground on either pipe racks or pipe sleepers. The pipework shall be protected from accidental damage in all areas where there is a risk of damage (e.g. roads).

Where underground pipework is unavoidable for example road crossings the pipework shall be installed in a pipe trench with adequate access for maintenance inspections. The trench shall be sealed so it is weather-proof, have a drainage slope, drain sump, level alarm to detect water ingress and facilities to install a submersible pump to remove accumulated water. The Contractor shall provide a local power point for the

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submersible pump and shall provide a suitable submersible pump as part of the scope of supply of this Contract.

17.2.9.2 Air, Water Service Stations For maintenance and cleaning purposes service stations consisting of hose connections for compressed air and water shall be provided.

17.2.9.3 Compressed Air Lines (instrument and service air) Compressed air lines shall be fully drainable and wherever possible, run with a minimum slope 1:500 away from compressors.

Drip legs with drain valves shall be provided at junction points, low points in the pipe route, and if necessary, at approximately 50 to 100 m intervals along the main line.

17.2.9.4 Service Piping Service piping headers shall be provided with an isolating valve from the supply main.

17.2.9.5 Underground Pipes The Employer prefers pipework systems to be mounted above ground wherever practicable.

All medium and small sized pipes that need to be below ground shall be run in open concrete channels that are arranged to have effective drainage. These pipe channels shall be fenced and traffic crossings and walkways shall be provided wherever necessary. If in specific areas the pipes must be directly buried in the ground this shall be subject to review and approval by the Employer.

Corrosion protection of underground pipework shall be approved by the Employer.

Pipelines shall be completely tested (hydrostatic, leak and porosity tests) and accepted by the Employer and approving authority before any filling of trench.

17.2.9.6 Temporary Strainers The Contractor shall provide temporary strainers on the inlet side of all major plant and equipment where permanent strainers are not provided. Strainers that slip between flanges shall be provided. The strainers shall remain in place until the Employer approves removal.

17.2.9.7 Wall Boxes and Collars Wall boxes and collars shall be provided for all penetrations through walls and floors.

Pipes passing through roof collars shall be provided with an approved weatherproof hood and cowl. Floor collars shall extend to 200 mm on concrete floors and 100 mm on steel grating above the floor level and the pipes shall be fitted with hoods where required. Weather flashings shall be fitted where required.

The boxes and collars shall not restrict any thermal expansion of piping.

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17.3 Material

17.3.1 General All material used shall be new, of best quality, most suitable for working under the specified conditions and it shall withstand the variations of temperature, pressure and atmospheric conditions arising under working conditions. No welding, filling or plugging of defective parts will be permitted without the permission in writing of the Employer.

Carbon steel pipes shall have a minimum corrosion allowance of 1.0 mm. Possible higher allowances shall be adopted based on the process requirements. Due care shall be taken to include thinning allowance for bends etc.

For a piping line handling two phase mixture a 5% chrome alloy steel piping material shall be used. The pipe material for the systems specifically identified in Chapter 17.2.1 shall be manufactured using a seamless process.

17.3.2 Marking All pipes and pipe fittings shall be marked with material identification markings so that all material can also be identified after cutting. The Contractor is shall not erect any material which cannot be identified. The Contractor shall submit to the Employer a procedure detailing of how the transfer of material identification marks is controlled.

17.3.3 Storage and Protection During transportation and storage the pipes and pipe fittings shall be protected against corrosion and dirt.

Pipes in storage shall be dry and free from corrosion, shall be protected internally in an approved manner and shall be stored off the ground. Prior to fabrication in the shop or in the field, scale or any foreign material shall be blown or swabbed from the interior of the pipe. After fabrication all open ends shall again be plugged, capped or otherwise sealed. All loose fillings, slag, sand, dirt, oil, grease or other foreign substances shall be removed from the interior and the exterior surfaces of all pipe fabrication prior to installation and/or coating.

Internal surfaces of valves shall be suitably protected and protectors shall be installed on valve ends or other speciality ends at the factory. Protection shall not be removed until the valves or specialities are installed. Valves and specialities shall be stored off the ground and protected from foreign elements.

17.4 Fabrication and Erection

17.4.1 General The following requirements are applicable for both shop fabrication of pipework, site fabrication of pipework and site erection of pipework.

All pipework shall be fabricated to the requirements of the approved design code. Prior to commencing erection the Contractor shall submit to the Employer for approval an Inspection and Test Plan for the fabrication, erection and testing of the

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pipework. Separate inspection and test plans shall be submitted for shop fabricated pipework and for site fabrication, erection and testing of pipework. Separate inspection and test plans shall be submitted for each fabrication shop and for each site fabrication and/or erection subcontractor.

Sub-contractors selected for off-site fabrication shall be approved by the Employer. For systems identified in Chapter 17.4.2 below the sub-contractor shall submit supporting documents to demonstrate their fabrication capability, quality control procedures, code approval certificates and provide a reference list of completed work.

All welding procedures, welders and welding machine operators shall be qualified to the applicable pipework design and fabrication code.

For both off-site fabrication and on-site fabrication and erection the Bidder shall submit the following documents for the selected sub-contractors to the Employer:

• Company financial report for the previous three years

• Company brochure

• Company quality manual

• ASME certificates and ISO 9000 series certificates

• Organisation chart for the project

• CV of key personnel on the organisation chart

• Reference list of similar projects

• Details of available erection equipment

• Welding consumable control procedures

17.4.2 9% Chrome Material – ASME Grade 91 and Grade 92 Materials This section is applicable for ASME Grade 91 and Grade 92 modified 9% chrome material and similar material manufactured to other internationally recognised codes. Note that material manufactured to any code other than the ASME or ASTM codes shall require Employer approval prior to purchase. These requirements in this Sub-section are in addition to the requirements of the section for Piping and are applicable for shop fabrication and for site erection work.

The Bidder shall include in his proposal a list of all pipe systems that he proposes to fabricate from ASME Grade 91 and Grade 92 material.

Pipework material suppliers shall be selected from a list of material suppliers that has been approved prior to award of Contract.

Pipework design, fabrication and testing shall comply with ASME B31.1.

Pipe material shall be supplied with mill certificates that confirm that the raw material hardness shall be within the range 190 – 250 HBN.

Welding consumables shall comply with the requirements of ASME IX however the Nickel content should not exceed 0.4% and the combined Nickel + Manganese should not exceed 1.2%.

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Flux core arc welding shall only be used with shielding gas. Flux core arc welding shall not be used for root pass application without backing or back gouging and welding. Shielded metal arc welding shall not be used for root pass application without backing or back gouging and welding.

Weld preheat shall be applied to the requirements of ASME B31.1. Pre-heat shall preferably be applied by electric resistance or induction heating and the preheat temperature shall be recorded by thermocouples. Gas heating shall only be used if it is not possible to use electric resistance heating coils or induction heating, e.g. for tubes and small bore pipework ≤DN50. Heating by an oxygen rich (oxy-fuel) flame is prohibited.

The maximum inter-pass temperature shall not exceed 316 deg. C.

All welds shall be adequately supported to ensure that no stresses can be applied to the weld.

Welding shall be continuous, however if an interruption is unavoidable then the following shall apply for welds where a minimum of 10mm thickness of weld is deposited or at least 25% of the weld groove is filled:

• For weld deposit thickness equal to or below 50mm the weld shall be held at 260 to 316 deg. C for one hour before cooling under insulation to a temperature below 93 deg. C.

• For weld deposit thickness above 50mm the weld shall be held at 260 to 316 deg. C for two hours before cooling under insulation to a temperature below 93 deg. C.

Prior to recommencing welding the weld shall be examined to ensure that there are no cracks in the weld. Pre-heating shall be applied before welding resumes.

After welding is complete post weld heating shall take place as described above. However if the weld and base material thickness is below 13mm and the weld has been completed using only a GTAW process the weld can be cooled under insulation to a temperature of 93 deg. C without post heating.

Post weld heat treatment shall be conducted to the requirements described in ASME B31.1 Clause 132 and Table 132. Sufficient thermocouples shall be attached to the area subject to post weld heat treatment to ensure an accurate temperature record is obtained. As a minimum there should be two thermocouples, one at top centre and one at bottom centre for pipework up to and including DN 250. For pipework over DN250 three equi-spaced thermocouples shall be used.

The control range for heating and cooling shall start and finish at 316 deg. C and the rate of heating and cooling shall not exceed 150 deg. C per hour.

Hardness testing shall be conducted after post weld heat treatment. Each test line shall consist of 5 readings in the sequence Base metal > Heat Affected Zone > Weld > Heat Affected Zone > Base Metal. For pipe sizes below DN100 there shall be one test line. For pipe sizes DN100 to DN250 there shall be two test lines diametrically opposite and for pipe sizes in excess of DN250 there shall be four equi-spaced test lines. All attachment welds to pipes shall have a minimum of one test line per weld.

The permissible harness range for the base metal is HBN 190 – 250. The permissible hardness range for the weld metal is HBN 190 – 280.

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Positive material identification shall be carried out on all pressure retaining welds.

17.4.3 Site Erection All piping shall be accurately installed according to the approved drawings. The joints and connections shall be accurately aligned and parallel without stress. At the assembly of the piping no stress shall be imposed on the equipment except the forces necessary to pre-set any expansion devices.

All piping shall be installed in a manner such that expansion will take place in the direction desired and so that vibrations will be minimised. No piping shall be cold pulled unless so indicated on the drawings that have been approved by the Employer. Cold pull (pull up cold) shall be clearly indicated on drawings submitted for approval.

Standard "Factory Made" fittings shall be used for all piping systems. Shop or site fabricated mitred fittings shall not be used.

No pipework shall be run in trenches carrying electrical cables.

All pipes, valves, fittings and specialities shall be properly protected. All damaged coatings shall be rectified after installation.

In general, no valves shall be installed with their stem directed downward. Valves with weld ends shall not be welded together. An intermediate pipe spool shall be used.

Welded connections shall be used as much as possible. The use of flanged or threaded connections is allowed only in cases where erection, maintenance, cleaning of pipe so demands. Threaded connections shall not be used in connection with high pressure steam and feed water piping.

Welding or flame cutting of galvanised pipe or pipe support material is not permitted.

Prior to assembly of various piping components it shall be confirmed that every piping component conforms to the specifications and the drawings.

Structure steel components shall not be cut, removed or damaged to make piping installation work easier.

During erection open ends of pipework shall be protected by temporary covers, which shall be securely fixed. When welding valves to the piping the valve manufacturer's recommendations shall be followed. During welding all valves shall be in the open position.

During installation, flanged joints shall be fitted up, after checking the alignment of the flange mating centres and confirming that the flange faces are parallel.

The bolt holes of the flanges to be welded to pipes shall be located symmetrically from vertical centreline in horizontal pipeline, and from plant north in vertical piping line, unless otherwise indicated on the drawings.

When declination exceeds any of the following limitations, flanged connection shall not be allowed.

• 3° angle difference between flange faces

• 5 mm declination of horizontal direction between flange centreline

• 5 mm distance between facing bolt hole, when a pair of bolt holes shall be faced and rolled.

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• Threads of bolt-nuts and contact surfaces of gaskets shall be covered with paste to prevent adhering, leakage, etc. These pastes shall be selected according to service fluids and/or temperatures.

Openings, such as flanged joints for pumps, compressors etc., shall be covered with thin plate or other blinds until final connection to prevent dust and other foreign matters from entering into the machinery.

Pipe supporting elements for pipes DN 50 and larger shall comply with the indicated location and equal to the shape shown on the drawings.

If temporary supports are required during construction, except those indicated in the drawings, they are subject to the approval by the Employer or the Engineer.

For cold pull gap the pipeline shall be supported and anchored according to the drawings before the cold pull gap is recorded, and before the pipelines are drawn together for the final connection.

For expansion joint space the pipeline shall be supported and anchored according to the drawings before the measurement between the two flanges is taken and the expansion joint installed.

17.5 Welding

17.5.1 General The Contractor shall employ a qualified welding engineer to prepare all welding procedures and weld repair procedures at fabrication shops and at the site prior to submission of the procedures to the Employer for approval.

Welders employed on any work, either at workshop or on site, shall be tested and formally approved to the requirements of the governing code or standard to be competent to carry out the type and standard of welding required before starting the work.

Each approved welder shall have an identification number.. All pipe welds shall permanently marked to indicate the welder(s).

All welding procedures and procedure qualification reports shall be submitted for the approval of the Employer. All expenses in connection with welder tests and procedure tests shall be covered by the Contractor.

Prior to commencing fabrication shop welding activities and site welding activities the Contractor shall submit the following documents and procedures for each pipework fabrication and erection subcontractor:

- Welding Procedures and Procedure Qualification Reports

- Welder Qualification Procedures

- General Welding Procedure

- Welding Consumable Control Procedure

- All Non-destructive Examination Procedures to be utilized

- Pre-heat and Post Weld Heat Treatment Procedures

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- Hardness Testing Procedure

- Positive Material Identification Procedure

- Specialist NDE company profile and NDE Inspectors qualifications.

17.5.2 Inspection of Welding The Contractor shall employ quality control inspectors to conduct welding inspections. All inspectors shall be formally qualified to a recognised code standard as required by the pipework design and fabrication code or qualified to American Society for Non-destructive Testing (ANST) for the inspection technique applied.

All welds shall be visually examined after completion by the QC inspector.

In addition the systems detailed below shall be fabricated to the requirements of Chapter 4.4 – Boiler Pressure Parts and shall be subjected to the non-destructive examination requirements listed in this clause.

- Main Steam Pipework.

- Hot and Cold Reheat Pipework

- Process steam pipework

- Steam Turbine bypass systems.

- Steam turbine integral pipework, extraction steam and gland steam lines.

- Feed water pipework including attemporator spray pipework.

- Turbine control oil pipework.

RT

%

UT

%

MT/PT

%

Circumferential butt welds 100 100* by exception

100

Branches with ND > 100 100 100

Nozzles, nipples etc ≤ 100 10 100

Instrument tappings 100

Socket welded joints 100

Pipework attachments 100

Pipe bending (induction) 100

RT = Radiographic Testing, UT = Ultrasonic Testing, MT/PT = Magnetic Particle Testing / Dye Penetration testing

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*UT shall only be used in lieu of RT where the joint configuration prevents RT for being effective and only with the Employer’s approval

For other pipework systems listed above in Chapter 17.2.1, 10% sample radiography shall be applied as detailed in Chapter 4.4.3 – Boiler Pressure Parts Non-destructive Testing.

Radiography procedures shall in accordance with the applicable requirements of the pipework design and fabrication code. Where there are no specific requirements stated in the design code the radiography procedures and radiograph film interpretation shall be in accordance with ASME Boiler and Pressure Vessel Code Section V and ASME B31.1.

The results of all weld inspections shall be recorded on a weld history sheet. Each weld history sheet shall include isometric drawings of the pipework identifying the welds and the inspection reports for all inspections and NDE processes plus post weld heat treatment charts hardness tests and positive material identification results if applicable.

The material composition of both parent and weld metal shall be confirmed after welding is complete for all pressure part components manufactured from micro-alloyed carbon manganese steels and all ferritic alloy materials. The inspection method shall be approved by the Employer.

17.5.3 Weld Repairs All weld repairs shall be carried out to a procedure approved by the Employer. If repairs are to be carried out by welding, dimensioned sketches of the excavated areas shall be prepared and the proposed repair procedure submitted for the approval of the Employer before any repair is started. Under no circumstances shall the repair be started until the approval of the Employer has been obtained. The areas shall be subjected to a suitable non-destructive test and on completion of the weld they will again be non-destructively tested. In the event that the repair requires all or any part of the item to be stress relieved, the non-destructive tests shall be repeated on any part deemed to have been affected by the stress relief.

17.6 Pipe Supports

17.6.1 General Requirements Standard supports shall be designed in accordance with material requirements. Materials to be used:

galvanised carbon steel for parts directly attached to piping (non-insulated piping)

carbon steel (insulated)

All support parts, which shall remain outside insulation, shall be delivered painted in accordance with good international engineering practice. The painting repairs after the completed erection work are included in the Works.

Adjustment of supports (springs etc.) is included in the Works. In general pipe supports and anchors shall be located at those points in the steel structure where provision has been made for the loads imposed. The cutting of floor or roof beams or

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the reinforcement in slabs will not be permitted. Piping attached to equipment shall be supported in such a way that the weight of the piping is not taken by the equipment. All supports above DN50 shall be shop fabricated and positioned before erection.

Supports, guides and anchors shall be designed so that excess heat will not be transmitted to the structural steel. Designs generally accepted as exemplifying good engineering practice, using stock or standardised prefabrication parts, shall be utilised wherever possible. Accurate weight balance calculations shall be made to determine the required supporting force at each hanger location and the pipe weight load at each equipment connection.

17.6.2 Pipeline Support Locations For the pipeline supports at least at the following locations shall be provided with such supports:

• at or near changes of direction on horizontal lines

• at or near branch connections on horizontal lines

• both sides of flanged joints on horizontal lines, unless otherwise specified

• both sides of flanged valves or instruments on horizontal lines, unless otherwise specified

• on one side of welded valves DN 80 and larger on horizontal lines.

• Structural connections for pipeline supports shall be preferably at the following locations:

• bayline beams (beams between steel columns)

• building columns

• underside of floor steel or top of curbed openings for vertical lines. Pipeline supports shall not be attached to:

• floor opening pipe-sleeves

• concrete block walls

• grating or checker plate

• equipment support steel

• an adjacent large diameter pipe line, except when approved by the Employer

• fittings, welding point and branch point, except when approved by the Employer

Supports for overhead pipe shall not be located on the floor below unless there is no possibility to otherwise support the pipe.

Pipe support attachments to existing beams, which would cause torsion stresses in beams, shall be avoided.

Pipe support attachments to existing columns, which would cause bending about the weak axis, shall be avoided.

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All large pipes and all long pipes shall have at least two supports each arranged so that any length of pipe or valve may be removed without any additional supports being required.

Variable springs shall be furnished with travel stops. The travel stops shall be factory installed at the "cold" position. Variable spring hangers shall have the cold set point and the hot condition point clearly marked on the hanger body. These markings shall be clearly visible from the adjacent walk-way.

For low temperature, non-critical systems, where vertical movements up to 50 mm are anticipated, pre-compressed variable springs design may be used. Where critical movement is greater than 50 mm a variable spring hanger shall be used. Where movements are of a small magnitude, spring hangers may be used.

Constant and variable support spring hangers shall have a minimum reserve movement of 15 mm beyond the minimum and maximum settings representing the calculated movement of the pipe from its cold position to its hot position.

All rigid hangers shall be provided with means for vertical adjustment after erection.

Where the piping system is subject to shock loads, such as thrust imposed by the actuation of safety valves, etc., hanger design shall include provision for shock absorbing devices of approved design.

Selection of vibration control devices shall be part of the Contractor's work. If vibration is encountered after the piping system is in operation, appropriate vibration control equipment shall be installed by the Contractor after Employer's approval.

17.7 Cleaning, Testing and Inspection

17.7.1 General Local Codes and Authorities having jurisdiction over any part of the work covered in the Contract shall apply.

17.7.2 Inspection

17.7.2.1 General On completion of the installation each pipeline or pipeline system shall be inspected and tested as specified on the pipeline nomenclature drawing and flushed or blown according to the procedures set out in the specifications.

All inspections shall be recorded on a "Pipeline Check-out Record", which shall be approved by the Employer.

When the Contractor has completed the installation he shall initiate the "Pipeline Check-out Record" sheet by filling in the pipeline number or system description; indicate the completion of installation by signing the Record; setting out the testing and cleaning required by the Specification; and if inspection or testing is required by special authorities such as Government or Insurance Agencies, naming the authority and stating the date that the testing is to take place ("independent agency").

After the Contractor has initiated the "Pipeline Check-out Record" sheet for a pipeline or pipeline system, the Employer shall inspect the pipeline or system to ensure that it

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meets all the requirements of the specification. The inspection shall be recorded on the "Pipeline Check-out Record".

In the case of inspection by a special authority the record sheet shall be submitted to the Employer at least 2 weeks in advance of the date of testing, and if necessary in this circumstance the sheet may be presented before the installation has been completed.

17.7.2.2 Independent Agencies (Government, Insurance, etc.) Where the specifications require the inspection, testing and/or cleaning to be performed in the presence of any authority having jurisdiction over the work, the Contractor shall identify the authorities having jurisdiction and shall notify them of the inspection, testing and/or cleaning in advance according to the requirements of the authority and shall obtain the signature of such authority on the sheet to indicate their satisfaction and approval.

The Contractor shall bear all costs caused by any independent agency or authority.

17.7.3 Requirements for Testing and Cleaning Before commencing the testing and cleaning of pipelines, the procedures to be used shall be submitted to the Employer for approval.

Pipelines that are to be hydraulically leak tested shall have temporary air vents and vacuum breakers located where necessary.

Pipelines, whose pressure limits exceed those of the equipment or vessel to which they are attached, must be isolated from these items during the pressure test.

When the Employer is satisfied that the requirements for testing and cleaning of the pipelines, as set out by the Contractor, are correct according to the specification this shall be recorded on the "Pipeline Check-out Record" and after that the Contractor may proceed with the testing and cleaning.

17.7.3.1 Testing All pipework shall be hydrostatically tested to 1.5 times the system design pressure. For low pressure systems with a design pressure below 3.3 bar(g) the test pressure shall be 5 bar(g).

For compressed air systems a pneumatic leak test to 1.1 times design pressure will be accepted.

Prior to conducting hydrostatic tests a Hydrostatic Test Procedure shall be submitted to the Employer for approval. The procedure shall include details of safety requirements

Prior to conducting a hydrostatic test the Contractor shall submit a Test Package for the system to be tested. This Test Package shall include the following:

• P&I Diagrams with the test boundaries clearly indicated, the location of all vents and drains to be used during filling and draining of the system, the location of the pressurising equipment, the location of the test gauge.

• Details of any temporary blind flanges or blanks to be installed,

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• The status of all valves, i.e. open or closed,

• The status of non-return valves.

• The status of safety or relief valves.

• Details of any permanent equipment excluded from the test e.g flow elements.

• Factory test certificates for equipment excluded from the hydrostatic test.

• The test medium and source shall be identified and test medium quality specified.

• The completed Weld History Sheet with supporting records as defined in Chapter 17.5.2.

• The Inspection and Test Plan with signatures to confirm that all inspections have been completed.

• Details of test equipment with calibration certificates.

• Details of post hydrostatic test storage and preservation requirements.

17.7.3.2 Cleaning All pipelines shall be cleaned. Cleaning shall generally consist of flushing the pipe hydraulically, or blowing the pipe with air or steam.

Care shall be taken to protect the Site and all facilities on the Site from damage resulting from the cleaning operation.

Unless otherwise agreed during Design Review the following pieces of equipment shall be left out during erection and replaced by temporary spool pieces before cleaning:

• Flow nozzles and lined magnetic flow meters

• All control valves except butterfly valves DN 150 and larger and V-ball valves DN 100 and larger.

• The following pieces of equipment shall either be left out during erection or removed from pipelines before cleaning:

• Orifice plates

• Attemperator nozzles

• Rupture discs

• Spray nozzles The following pieces of equipment shall be blanked-off or isolated before cleaning:

• Safety relief valves

• Instrument connections

• Equipment inlets and outlets

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17.7.3.3 Flushing Flushing shall consist of running clean water or flushing oil as specified through the pipeline either by gravity or by pump at a sufficient velocity to remove the dirt in the pipe, such flow to continue until in the opinion of the Employer the pipeline is discharging a clean fluid.

When pipelines are flushed into a vessel, the vessel shall be drained, cleaned and inspected by the Contractor, witnessed by the Employer, on completion of the flushing, and if such vessels are to be used as a source of supply for flushing another pipeline, the cleaning and inspection of the vessel shall be completed before such use.

Piping systems that require chemical cleaning and passivation shall have this done immediately prior to start-up, and after the chemical cleaning and passivation shall be flushed with a fluid that contains rust inhibitor.

The Contractor shall be responsible for the disposal of all flushing media in accordance with local statutory requirements.

17.7.3.4 Air Blowing Plant air supply lines and headers shall be blown with air from the plant air compressors or a similar source approved by the Employer.

Instrument air supply lines and headers shall be blown with oil- and water-free air.

Lines that are to be air blown shall be blown at a sufficient velocity to loosen all dirt and shall be blown until in the opinion of the Employer the discharge is entirely free from dust.

17.7.3.5 Steam Purge A steam purge of the boiler and the complete steam lines shall be carried out to remove the mill scale, slag and other foreign materials from boiler and the steam lines prior to initial operation of the steam turbine. The Contractor shall provide all necessary temporary pipework, equipment and connections.

Three months prior to conducting any steam purging the Contractor shall submit a detailed purge procedure to the Employer for approval. The procedure shall identify systems to be purged, how purging will be conducted, details of temporary pipework including design NDE and testing requirements for the pipework, flow calculations, disturbance factor, how cleanliness will be demonstrated, acceptance criteria, noise mitigation measures and safety measures.

The steam purge shall include all steam lines between the boiler and the steam turbine, the turbine bypass lines, the turbine seal steam system, and all other auxiliary lines that return steam into the main steam and water system.

The temporary pipework shall be designed to the requirements of ASME B31.1. All temporary pipework shall be hydrostatically tested to demonstrate system integrity.

The contractor shall supply all special valve inserts required to protect permanent plant from damage during the purge process.

Adequate sirens and notices shall be provided and suitable barriers erected to warn personnel of the steam blow. Noise during Steam blows shall not exceed the Noise

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level requirements at the site boundary for day and night of 60 dBA and 55 dBA respectively. The Contractor’s steam purge procedure which is subject to the Employer’s approval shall be submitted six months prior to steam purge. The procedure shall demonstrate that a mass velocity at least 1.25 times greater than which occurs during the boiler operation at BMCR is generated during the steam purge. The purge procedure shall include stress calculations to confirm the adequacy of the temporary pipework and supports and all purge flow paths with the location and setting of temporary and permanent plant valves indicated.

The purge procedure shall detail the target plate material and demonstrate that the material hardness is compatible with the turbine blade material.

The valve controlling the steam blow shall have an opening time suitable for creating adequate disturbance. Calculations for the disturbance factor shall be based on boiler conditions when the valve is fully open.

Disturbance factor shall be 1.25 for the main steam system using the following formula:

Disturbance Factor = Drag under Purge Flow

Drag under Max Steam Flow

= Wp2 x Vp

WR2 x VR

Where W = flow rate in kg/h

V = specific volume in m3/kg Suffix P is blow out condition

Suffix R is maximum steam flow condition

Steam lines and other lines that are to be steam purge shall be blown in the following manner and sequence:

1. Check that all spring hanger blocks are removed and that the cold load spring setting is according to the drawings.

2. Install temporary atmospheric vents and drains, anchors, guides and if required, target plates and have the installation approved by the Employer before commencing a steam blow.

3. Close the shut-off valves to steam trap assemblies.

4. Heat the pipe or system slowly to operating temperature and while the pipe or system is being heated, check that all expansion joints are working, that all expansion shoes and roller saddles are of the proper length and that floor and wall opening clearances are adequate.

5. As the pipe is being heated open all pipeline drains and slag pocket drains and clean them if necessary.

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6. Steam blow the lines for sufficient times at a sufficient velocity to loosen and remove dirt and scale.

7. Cool the pipe to the pre-agreed temperature listed during the Owner’s prior review and agreement of the proposed purge procedure.

Repeat steps 4), 6) and 7) above at sufficient times until in the opinion of the Employer the pipes are clean.

The method for checking the completeness of the steam purge including the acceptance criteria shall be described in the Bidder’s Proposal. The acceptance criteria shall as a minimum satisfy the requirements of the supplier of the steam turbine.

17.7.3.6 Cleaning Records When the Contractor has completed the cleaning operations, he shall record the operation, and if the cleaning is to the satisfaction of the Employer, the Employer will sign the Cleaning Records.

If any pipelines or vessels are flushed or blown into a pipeline or system that has been previously cleaned the pipeline or system shall be re-cleaned as set out herein, and a new Cleaning Record shall be filled out for the cleaning operation.

17.7.3.7 Employer’s Acceptance When the testing and cleaning are completed and approved by the Employer and by any special authority the Contractor shall remove all temporary piping and re-install the parts removed, and shall close valves to isolate the pipeline or section.

When the Employer is satisfied that all of the requirements for testing and cleaning have been properly completed, all of the parts re-installed, the Employer will indicate his satisfaction and approval by signing the inspection Record, and will mark the pipe to indicate that it has been completed and accepted.

17.7.4 Surface Treatment All carbon steel pipes and equipment without insulation shall be painted in accordance with good international engineering practice.

All pipework to be insulated shall be coated with a heat resistant primer to prevent corrosion prior to the initial start-up of the plant.

High temperature pipes shall be painted with heat resistant paint.

17.7.5 Identification of Erected Pipework Final marking shall be done to meet the requirements of the Employer and in such a way as the piping can be identified along the whole run. The pipe identification shall comply with the approved plant identification system.

Nameplates, delivered and installed, on tanks, vessels and valves shall be included in the Works.

The marking on pipes can be done by attaching tapes around the insulation cladding or painted on pipes at suitable locations. The tape should mark the flow direction, the flow media and the line code of the pipe.

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17.8 ocumentation and Drawings Plan and section drawings shall be made in scale 1:50.

Pipes larger than DN 50 shall be fully detailed. Pipes DN 50 and below shall be indicated by centre-line only.

Pipes shall be dimensioned to the nearest column centreline and elevation shall be shown.

Position numbers of pipelines and valves shall be marked.

Following connections and details shall be shown with tag numbers:

• measurement points

• local measurement points

• sampling points

• dosing points

• drain and vent points Piping drawings should also indicate the following for reference:

• cable routes

• heating and ventilation ducts During detail engineering piping design shall be finalised.

Following documents and tasks shall be done:

• isometric drawings, DN 50

• pipe support locations (piping drawings)

• pipe support drawings

• fabrication drawings for special fittings

• "as built" drawings

During the pipework erection the Contractor shall establish a Field Change Notification system. The system shall be approved by the Employer prior to the start of site activities. The Field Change Notification system shall ensure that all field changes are correctly recorded and the changes are made to the “as built” drawings.

The Contractor shall deliver all the final documentation for the piping systems to the Employer before the piping is taken over.

17.9 Instrument Connections

17.9.1 Arrangement Process connections for instruments, chemical dosing and sampling shall be attached to the piping at locations shown in the final P&I-diagrams. The location of connections shall carefully be considered as to process demands, accessibility and mechanical strength. Connections shall not be placed in piping bends or elbows.

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High pressure connections (40 bar(g) and above) shall always be fitted with two shut-off valves at the connection point.

Local pressure gauges shall be provided with an isolation valve. Where determined by the process, pulsation dampers and siphons will be provided.

For the following three requirements the extent of supply shall be reviewed and agreed during design review. Adequate indications shall be provided to ensure safe local operation and maintenance:

• Local pressure gauges shall be installed at the suction and pressure sides of all pumps and fans, pressure vessels, steam headers, heat exchangers, tanks and vessels.

• Local temperature gauges shall be installed using thermo-wells at both sides of all heat exchangers, pressure vessels, steam headers, tanks and vessels.

• Local level indicators shall be installed on all tanks, vessels and tube heat exchangers.

• Local pressure gauges shall be installed at the suction and pressure sides of all pumps and fans, pressure vessels, steam headers, heat exchangers, tanks and vessels.

Differential pressure instruments shall be installed with five or three valve manifolds.. Single pressure measurement transmitters and switches shall have a two valve manifold.

Chemical dosing connections shall be fitted with shut-off valve and check valve and sampling points with a shut-off valve at the connection point.

Sample point for steam systems shall also include a flow restriction orifice. The sample delay time shall not be sufficiently long that control of chemical dosing is adversely affected and shall under no circumstances be longer than 30 minutes.

17.9.2 Materials Materials of the process connections shall be of the same quality as the pipe. Instrument manifolds will be stainless steel.

All connections shall be designed according to the pressure and temperature specified for the pipe to which they are connected. Strength calculations shall be performed.

17.10 Valves

17.10.1 General All valves shall be manufactured and tested to a recognized international code. ASTM, ASME, ANSI and MSS standards shall be considered to be the minimum requirement. In addition fire protection valves shall meet the requirements of the relevant NFPA code. Valve testing shall be conducted to the requirements of API 598 and the results of the tests shall be made available to the Owner.

The valves shall be suitable for the maximum design conditions of the system in which they are installed and shall be capable of withstanding the hydrostatic test pressure of the system.

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Valves shall close against the full flow and design pressure and open against the full design pressure of the system in which they are installed.

A Valve List shall be submitted with valve tag numbers, system operating and design pressure temperature and flow details, valve size, valve materials and manufacturer.

The Contractor shall minimize the number of different valve suppliers to optimize the spare parts requirements for valve maintenance.

For welded valves the valve end connections shall be compatible with the material of the associated pipe.

The selection of valve trim material shall be based upon tensile strength, chemical stability and corrosion and erosion resistance at operating conditions, hardness and toughness, coefficient of expansion relative to the valve body and sufficient difference in properties of the seat and disc facing material to prevent seizing.

The seat material shall retain adequate compressive properties at operating temperature and be immune to growth or chemical change due to temperature. The seat shall also resist oxidation to retain a smooth surface essential for tightness.

All valves required for the regular operation and maintenance of the plant shall be readily accessible from permanent platforms.

Suitable lifting points shall be provided on heavy valves or valve components to facilitate lifting for maintenance.

All isolating valves shall be capable of being locked in both the open and closed positions for the purposes of plant isolation. The Contractor shall provide the necessary devices and locks, which shall not incorporate small loose components.

All valves shall be arranged so that the handwheel moves in a clockwise direction to close the valve. The face of each handwheel shall be clearly marked with words “open” and “close” and shall be provided with an arrow to indicate direction for opening and closing. Valves shall not be fitted with the stems below the horizontal. An indicator shall be fitted to each valve and each extended spindle to clearly show the position of the valve.

Hand wheels and gear reducers shall be sized to permit operation of valves without using hand wheel spanners with the full pressure differential and with the force applied to the handwheel not exceeding 250 N. All valves 300 mm and above shall be provided with gear reducers.

All parts, particularly seats and discs, which are subject to wear, corrosion or other deterioration which require adjustment, inspection or repair, shall be accessible and capable of reasonably convenient removal when required. All valve internals shall preferably be capable of being removed with the valve body in position.

Where desirable to protect valve rising spindles against ingress of dirt, or where the position of the valve may create a hazard to operators when the spindle is extended, suitable covers shall be provided. All valve stems for valves that are installed in an outdoor location shall have a weatherproof protection cover.

High pressure isolating valves shall be arranged in tandem. Two valves in series shall also be provided for drains, vents and sample lines. All test points and pressure gauge connections shall be provided with double isolating valves.

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All isolating shall be capable of being operated from floor level. Where valves are located in pits or enclosures deemed to be confined spaces, extended operating spindles or similar devices shall be provided. . All valves which are required to open or close during normal operation of the plant, including start up and shut down shall be equipped with an actuator.

All power operated valves shall have position indication in the DCS. The hand operating and motor operating mechanism shall be interlocked in such a way that the hand operating mechanism shall be disconnected before the motor can be started.

Valves shall be fitted with permanent identification plates showing the valve function, number and direction of closure. Each valve shall be permanently marked with the code designation of valve, body material, manufacturer’s serial number, nominal bore and the nominal pressure/test pressure and temperature. Where valve flow is only in one direction the flow direction shall be clearly indicated on the valve body.

Flanged valve bolts shall be to the requirements of ASTM A 193 and 194 as a minimum requirement.

17.10.2 Dimensioning Minimum pressure class for steam and condensate valves is PN 16. Minimum pressure class for stainless steel valves is PN 10. Valves shall be of full bore type.

Welding end dimensions shall be prepared for butt-welding. Welding end dimensions shall be equal to the dimensions of the connecting pipe; neither use of transition piece nor welding end preparation is accepted.

Steam and condensate Valves equal or greater than DN 65 shall be gate valves with butt-weld ends.

Small bore valves shall be globe valves with butt-weld ends.

Materials shall be according to pipe material

Large steam valves shall be furnished with by-pass valves. Connections for by-pass valves shall be welded to valve bodies.

Steam and condensate Valves shall be furnished for drainage, with minimum of DN 25

If required by construction of the valve, the valve shall be furnished with body safety valve

Demineralised water Valves equal to DN 100 and greater shall be gate valves with butt-weld ends or butterfly valves between flanges.

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Valves below DN 100 shall be ball valves with butt-weld ends.

Check valves shall be between flanges

Material requirement is AISI 316 or equal.

Cooling water Valves equal or greater than DN 100 shall be butterfly valves between flanges.

Valves below DN 100 shall be ball valves with butt-weld ends

Check valves shall be between flanges

Material requirement is AISI 316 or equal

Sampling and chemical dosing Valves shall be globe or needle valves with butt-weld ends

Check valves shall be with butt-weld ends.

Below DN 65 socket weld type is acceptable.

Material requirement is AISI 316L or equal

Steam traps Low pressure steam traps shall be thermostatic /thermodynamic or float traps with flanges

Body material of low pressure traps shall be carbon steel

17.10.3 Motorised Actuators All ball and butterfly valves shall be equipped with gear and hand wheel, if size is DN 150 or greater.

Actuators shall be equipped with:

• 3-phase 50 Hz motors

• IP67 enclosure

• travel limit microswitches (open/close)

• torque limiting microswitches

• local and remote (DCS) fault indication

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• remote (DCS) 4-20mA position transmitter however not for valves subject only to on/off (open or closed) operation.

• local position indicator

• remote/off/local selection, with padlocking facility

• open/stop/close local selection with local and remote (DCS) status indication

• remote operation and monitoring from the plant DCS

• The electrical actuators shall be equipped with integrated control and power sections locally installed at the actuators.

• Binary actuators shall have short time ratings appropriate to duty cycle type S2 10 min. to IEC 60034-1, and a maintenance free interval better than 10,000 open/close cycles or better as required by the process.

• Modulating actuators including inching shall have a rating appropriate to duty cycle type S4 20% 1200 cycles/h to IEC 60034-1 and a maintenance free interval better than 50,000 hours in normal operation or better as required by the process.

17.10.4 Marking The valves shall be permanently marked with:

• equipment tag number

• nominal size/pressure

• name of manufacturer and type code of valve

• serial number

• construction material, or code by which the material can be identified

• flow direction if needed for valve installation

• permitted operating temperature zone valve number (Employers position number)

17.11 Thermal Insulation

17.11.1 General Thermal insulation shall refer to the supply and application of all heat insulation materials together with all necessary associated materials such as fastenings, vapor barriers, jacketing cements, adhesives, etc., which are used as insulating materials for piping, vessels, ductwork and equipment for the purpose of reducing heat loss, prevention of condensation and for personnel protection.

All insulation materials for hot application shall be of non-flammable insulation materials, compatible with the surface being covered and shall not cause corrosion of the covered material. All insulation material shall be chemically inert and remain so in the event of being saturated with water.

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Asbestos insulation material or insulating material containing asbestos is not acceptable.

Insulation for condensation prevention shall be applied to equipment, plant, piping, etc. operating at temperatures below the maximum dew-point where condensation could form to the determent of plant structures or equipment or cause discomfort to operating personnel.

The insulation shall generally be in accordance with ASTM C547 for pipework DN200 and below and ASTM C592 for pipework above DN 200 or an equivalent international standard. The Contractor shall submit a detailed insulation material specification for approval during the design phase. If the Contractor nominates an alternative material specification then the Contractor shall demonstrate that it is equal to the ASTM standards.

The Contractor’s material specification shall list the materials he proposes to use, their thermal conductivities calculated in accordance with the approved standard for the operating temperatures of each application, the thickness and density of each material used and where two layers of dissimilar materials are used, the actual interface temperature.

The insulation material shall be durable and meet the service requirements of the plant for the full life of the plant.

Thermal heat loss shall not exceed 200W/m2.

Thermal insulation shall be applied to all surfaces that operate at, or can intermittently operate at a temperature in excess of 60°C. Insulation shall be provided for heat conservation and personnel protection. The surface temperature of any insulated surface shall not exceed the ambient air temperature by more than 25 degrees centigrade.

All equipment and piping with an operating temperature over 60°C shall be insulated by thermal insulation. This does not apply to places, which for functional reasons must be left without insulation.

For personnel protection, insulation shall be applied to lines that are normally 60°C or less, but may reach a higher temperature as a result of abnormal conditions or intermittent operation.

Where lines are not insulated for operational reasons (e.g. steam vents and drains) insulation for personnel protection shall be applied only to parts of the line that are within 2.5 m above any floor, platform, or other normal access way, or within 1.2 m horizontally and up to 2.5 m above the edge of any access way.

17.11.2 Insulation Design The type and thickness of insulation materials used shall be entirely suitable for the particular application and shall be subjected to approval by the Employer. Sprayed on “asbestos free” insulation shall be provided on irregularly shaped items of equipment. The type of jacketing to be used shall be capable of withstanding the site atmospheric conditions without surface deterioration. All insulation shall be covered with at least 0.6 mm thickness aluminium sheet jacket for piping and vessels. However, at

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locations where persons might cross over pipes or install temporary access for maintenance the aluminium sheets shall be at least 1.2 mm thickness.

Spacers shall be provided for pipework with an insulation thickness greater than 60mm to secure the insulation evenly all around the surface to be insulated. Spacers shall be installed every meter. The spacers shall be insulated to prevent heat migration for the pipe to the aluminium sheeting. Clamp rings shall be secured with galvanised bolts and nuts, minimum size M8.

Where aluminium sheeting is used, provisions must be made to avoid any electrolytic action.

Aluminium sheets shall be secured with a minimum of five stainless-steel pan head self-tapping screws per meter run using UV resistant washers. Longitudinal seams shall be installed to prevent water ingress. Sufficient overlap shall be allowed at all seams for expansion.

All outdoor insulation shall be completely weather tight sealed. All joints in aluminium sheeting shall have a rolled edge to prevent water ingress by capillary action.

All valves and fittings shall be covered with insulating materials of the same kind and thickness as that specified for the pipelines in which they are installed.. For reducer fittings the material thickness shall be that for the larger diameter pipe.

Removable sections of insulation shall be provided over removable plates, lifting lugs, access doors or areas where inspection data appears and in any other area specified. Insulation shall be applied in a manner which will allow withdrawal of the removable part without damage to such sections or to adjacent insulation. Equipment nameplates mounted on brackets extending from the body shall be framed in with insulator so as to leave the nameplates exposed ready for identification.

The insulation and cladding of the items requiring maintenance shall be designed to permit quick and easy removal. The cladding shall have stainless steel adjustable toggle catches to facilitate quick removal.

Insulation for vertical pipes shall be supported by rings at a maximum spacing of two meters. Aluminium sheets shall be supported by “S” hooks and have sliding joints as required for thermal expansion of the pipework.

During the design phase the Contractor shall submit a detailed insulation design document. The document shall detail the following:

- Design conditions

- insulation materials to be used including material data

- standard material thicknesses

- standard installation material e.g. wire mesh, tie wire, jacketing sheets, screws

- standard details for flanges, valves, instrument tapings, insulation support and spacer materials

- a matrix table giving insulation thickness for given pipe sizes and service conditions

- typical installation drawings

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17.11.3 Installation The following requirements are applicable for both factory and site installed insulation.

The finished insulation shall be neat in appearance. Penetrations through the aluminium sheets shall be neatly finished with an edge strip so the cut sheet is not visible.

Piping and equipment must be clean, dry and free from grease, dirt, loose rust or scale before application of insulation materials. Surfaces shall be power brush cleaned to remove loose materials prior to application of insulation. A stainless steel brush shall be used for stainless steel materials.

Insulation shall be adequately protected again water and dirt during installation. Any material that suffers rain damage during installation shall be replaced.

Aluminium sheets shall be protected against contact corrosion from tie wire or wire mesh.

A silicone based sealant shall be applied to all joints on outdoor installations and indoor installations that could be exposed to water.

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