Bolt Torque- Foster Wheeler Standard

8/17/2019 Bolt Torque- Foster Wheeler Standard

1/18


2/18

PARADIP REFINERY PROJECT

PROJECT SPECIFICATION A CONTROLLED BOLT TIGHTENING

PDRP-8440-SP-0011PAGE : 2 of 18

REV : F1

PDRP-8440-SP-0011 REV F1.doc DSN: 1863

CONTENTS

SECTION SUBJECT Page No.

1.0 SCOPE................................................................................................................... 3

2.0 DEFINITIONS......................................................................................................... 3

3.0 FLANGED JOINTS TO BE CONSIDERED FOR CONTROLLED TIGHTENING . 4

4.0

WHEN TO APPLY THE PROCEDURES............................................................... 5

5.0 JOINT PREPARATION.......................................................................................... 5

6.0 BOLT STRESS CALCULATION ........................................................................... 6

7.0 HYDRAULIC TENSIONING................................................................................... 7

7.1 Location of Prepared Bolts ..................................................................................8

7.2 Sequence of Tensioning 100% Bolt Sets ............................................................8

7.3 Sequence of Tensioning 50% Bolt Sets ..............................................................9

7.4 Sequence of Tensioning 25% Bolt Sets ..............................................................9

7.5 Checking Completed Joints ...............................................................................10

8.0

TORQUE TIGHTENING....................................................................................... 10

8.1 General ................................................................................................................. 10

8.2 Torque Tightening Technique............................................................................11

8.3 Location of Prepared Bolts ................................................................................11

8.4 Torque Values......................................................................................................11

8.5 Torque Tightening Sequence.............................................................................11

8.6 Checking Completed Joints ...............................................................................12

9.0 ASSEMBLY QUALIFICATION PROCEDURE .................................................... 12

10.0 INFORMATION REQUIRED BY A SPECIALIST BOLTING CONTRACTOR..... 13

11.0 INFORMATION TO BE PROVIDED BY A SPECIALIST BOLTING

CONTRACTOR (BEFORE WORK COMMENCES) ............................................ 13

12.0 DOCUMENTATION TO BE PROVIDED BY SPECIALIST BOLTINGCONTRACTOR ON COMPLETION OF WORK .................................................. 14

FIGURE 1: FLANGE BOLT TIGHTENING SEQUENCE ....................................................... 15

TABLE 1: GUIDE VALUES OF RESIDUAL BOLT STRESSES FOR VARIOUS BOLTINGMATERIALS ............................................................................................................................ 16

TABLE 2: SUGGESTED TORQUE FACTORS ................................................................... 17

TABLE 3: ACCEPTABLE LUBRICANTS............................................................................ 18


3/18



PDRP-8440-SP-0011PAGE : 3 of 18

REV : F1


1.0 SCOPE

This standard covers the requirements for the controlled tightening of flanged joints using hydraulic bolt tensioners or torque wrenches. (Torque wrenchesmay be hydraulically, pneumatically or manually powered).

It is recognised that vessel/heat exchanger manufacturers and specialist boltingContractors may have their own bolt tightening procedures. These may be usedfollowing review by and written approval from the Buyer.

In the absence of approved bolt tightening procedures the requirements of thisstandard apply to the controlled tightening of bolted joints

2.0 DEFINITIONS

Throughout the document the following definitions apply:-

2.1 HydraulicTensioning

The application of bolt load by stretching the bolt usinga hydraulic nut at the free end of the bolt followed byhand tightening of the service nut

2.2 TorqueTightening

The application of bolt load by rotating the in service nutusing a torque wrench

2.3 AppliedLoad/Stress

The maximum load/stress applied to the bolt during thetightening procedure

2.4 ResidualLoad/Stress

The load/stress in the bolt on completion of thetightening procedure


4/18



PDRP-8440-SP-0011PAGE : 4 of 18

REV : F1


3.0 FLANGED JOINTS TO BE CONSIDERED FOR CONTROLLED TIGHTENING

Flanged joints which comply with any of the criteria listed below shall be madeusing a controlled tightening procedure. Joints to be considered include

a) pipeline flanged joints

b) pipeline to vessel joints

c) vessel joints including manway covers and girth flanges

d) equipment joints.

Each joint shall be identified on the piping isometric for line joints, vesseldrawing for line to nozzle, manway and girth joints and on the equipmentdrawings/documentation for equipment items.

3.1 Individually designed flanged joints where a required bolt stress is a designrequirement.

3.2 Joints with a bolt size greater than or equal to 38mm.

3.3 Joints with bolt greater than or equal to 25mm and below 38mm, when

a) Joints have tapped holes.

b) Items not subjected to hydrotest, eg joints for equipment manholes,equipment mounted temperature, pressure and level instrumentation,line mounted temperature connections, online instrument joints likecontrol valves, safety valves, compressor volume bottles

c) Joints involving two sets of gaskets with one set of bolts, eg orificeflange joints, joints with spectacle blinds, spacers, flangeless wafercheck valves, wafer type butterfly valves

d) Tie-in joints with other Contractors and package vendors.

3.4 Pipeline sizes equal to or greater than as shown in the table below

Design Temperature (deg C) Cyclic

Rating Class 430 C*

150 A,H,Q,S None 20” 6” 6”

300 B,J,R 22” 16” 6” 6”

400 C,K 18” 14” 6” 6”


5/18



PDRP-8440-SP-0011PAGE : 5 of 18

REV : F1


600 D,L 16” 12” 6” 6”

900 E,M 14” 8” 6” 6”

1500 F,N 6” 6” 6” 6”

2500 G,P 4” 4” 4” 4”

Note 1) Below 340 deg C the bolt size governs the requirement forcontrolled tightening. (i,e. Bolt size >= 38mm).

2) Cyclic pressure and/or temperature is coded C* in the line classlist.

3) Line class list code for critical joints is T*.

4) In some cases application of the criteria specified in 3.3 abovemay identify a large number of critical joints. IOCL should beconsulted in cases where this occurs.

(Note Codings* to be defined for contract use).

3.5 Any other flanged joint defined as critical by IOCL

4.0 WHEN TO APPLY THE PROCEDURES

It is not a requirement of this standard to apply the following procedure beforehydrotesting or flushing/cleaning operations. Controlled tensioning or tighteningof bolts in a flanged joint which complies with section 3 above, shall be carriedout prior to the introduction of process fluids. (ie final make up)

However, the procedure may be usefully applied to reduce spurious leaksduring pipeline cleaning and testing.

This procedure does not apply to "hot bolting".

5.0 JOINT PREPARATION

The final success of the completed joint is greatly dependant on the initialpreparation of the joint components. In addition to good engineering practicethe following must be covered in the inspection of the components before the joint is "released" for final controlled tightening.

5.1 Bolts for hydraulic tensioning shall be the standard length plus one nut length toaccommodate the hydraulic puller.

5.2 Nuts shall run freely (by hand) along the working length of the bolting.


6/18



PDRP-8440-SP-0011PAGE : 6 of 18

REV : F1


5.3 Alignment of the flanges shall be measured and any misalignment greater thanas set out below shall be corrected before starting to complete the joint. Underno circumstances shall the tensioning procedure be used to correctmisalignment of flanges or pipework.

Max allowable translation of

flange centre lines and faces 1.5 mm

Max allowable out of parallelalignment of flanges faces

0.25mm/100mm flange diameter,1.5mm max

Bolt hole alignment (1/8") max offset with boltsmoving freely in bolt holes

5.4 Ring joint grooves shall be dimensionally checked to ensure compliance withthe appropriate standard.

5.5 Check that prepared bolts are in the correct location (see section 7.1 fordetails).

5.6 The metallurgy of any metallic gasket to be certified.5.7 Cleanliness of joints to be verified and/or remedied.

6.0 BOLT STRESS CALCULATION

The preferred method of checking the residual bolt stress in a completed joint isby calculation from a micrometer or vernier measurement of the elongation ofthe bolt. Bolts to be used for elongation measurements (maximum of four per joint) shall be minimum standard bolting for the joint with the following additional

preparation.

a) Machine both ends of the bolt to a surface finish of 125 microns.

b) Countersink both ends on the bolt centreline to accept an externalmicrometer.

It should be noted that the following calculation only requires a comparative boltlength measurement to obtain the calculated residual bolt stress. Boltelongation during tightening is of the order of tenths of a millimetre per metre.


7/18



PDRP-8440-SP-0011PAGE : 7 of 18

REV : F1


The residual bolt stress shall be calculated from the following formulae:-

Residual Stress = Bolt Elongation * Young’s Modulus / Bolt EquivalentLength

Where Young's Modulus = 207,000 N/mm2 for B7, B16 bolts

= 193,000 N/mm2 for stainless stud bolts.(B8, B8M)

Bolt equivalent length = Nut face distance plus one nut height mm

Values of residual stress for various bolting materials are given in table 1.

Attention is drawn to the fact that class 900, 1500 and 2500 RTJ flanged jointshave a lower residual bolt stress than RF joints for the same bolting material.This reduction is necessary to avoid excessive deformation of the flange facingby the joint ring.

Bolt stress and elongation measurement using ultrasonic techniques shall only

be used following approval of the technique by the Buyer.

7.0 HYDRAULIC TENSIONING

Hydraulic tensioning is the preferred method to be employed where controlledflanged joint tightening is required. In addition, 100% tensioning is preferred(i.e. a bolt tensioner on each joint bolt). Bolt tensioning heads may be fitted onalternate sides of the flange.

Where clearance between bolts is restricted, 50% or 25% tensioning ispermissible provided that:-

for 50% tensioninga) tensioners are fitted on alternate bolts and

b) the tightening procedure is completed in steps of 40%, 70% and100% of the required applied bolt stress on the first bolt set.(See 7.3).

for 25% tensioning

a) a minimum of four heads are used

b) heads are evenly spaced round the bolt circle.

c) the tightening procedure is completed in steps of 40%, 70% and

100% of the required applied bolt stress on the first bolt set. (See7.4).


8/18



PDRP-8440-SP-0011PAGE : 8 of 18

REV : F1


In practice, the applied bolt stress is greater than the residual bolt stress. Thereduction in bolt stress after releasing the hydraulic puller is caused byrelaxation of the bolt system. To attain the required residual stress it ispermissible to use an actual bolt stress up to 20% greater than the residualstress given in Table 1.

7.1 Location of Prepared Bolts

To enable bolt stress to be checked, prepared bolts as described in section 6shall be fitted to each flanged joint which is subject to controlled tensioning (ortightening).

The minimum required number and location of the prepared bolts for variousflange bolt arrangements is shown on Figure 1.

7.2 Sequence of Tensioning 100% Bol t Sets

Fit tensioners to all the bolts and tension to give 40% of the required appliedbolt stress. Check the flange alignment to ensure that the gap is closing upevenly. Any misalignment up to the limits stated in section 5.3 can be correctedby adjusting individual bolt loads. Misalignments greater than those given insection 5.3 must be investigated and corrective action taken before proceeding

with the tensioning process.

Continue to increase the pump pressure until 70% of the applied bolt stress isachieved and again check the flange alignment.

Provided satisfactory checks have been made, increase the pump pressure toachieve 100% of the applied bolt stress.

Tighten the service nuts and reduce the pump pressure to zero. Repressurisethe tensioners to give 100% of the applied bolt stress and tighten the servicenuts if necessary. Repeat this step once more.

Measure and record the lengths of the prepared bolts and calculate the residualstress in these bolts as described in section 6.

The bolt stress is proportional to the hydraulic pump pressure, thus the 40%and 70% bolt stresses are achieved when the pump pressure is 40% and 70%respectively of the pump pressure necessary to achieve the required appliedbolt stress.

There is no requirement to measure bolt elongation at the 40% and 70%intermediate steps.


9/18



PDRP-8440-SP-0011PAGE : 9 of 18

REV : F1


7.3 Sequence of Tensioning 50% Bolt Sets

Identify the 50% bolt sets using the letters A & B working consistently round theflange.

Fit tensioners to all the reference A bolts and tension to give 40% of therequired applied bolt stress. Check the flange alignment to ensure that the gapis closing up evenly. Any misalignment up to the limits stated in section 5.3 canbe corrected by adjusting individual bolt loads. Misalignments greater thanthose given in section 5.3 must be investigated and corrective action takenbefore proceeding with the tensioning process.

Continue to increase the pump pressure until 70% of the applied bolt stress isachieved and again check the flange alignment.

Provided satisfactory checks have been made, increase the pump pressure toachieve 100% of the applied bolt stress . Tighten the service nuts and reducethe pump pressure to zero.

Repressurise the tensioners to give 100% of the applied bolt stress and tightenthe service nuts if necessary. Repeat this step once more.

Move the tensioners to the reference B bolts. Pressurise the tensioners to give100% of the applied bolt stress tighten the service nuts and reduce the pumppressure to zero. Repeat this step twice more.

Move the tensioners back to the reference A bolts and reapply the pressure togive 100% applied bolt stress. Tighten the service nuts if necessary.




7.4 Sequence of Tensioning 25% Bol t Sets

Identify the 25% bolt sets using the letters A, B, C and D working consistentlyround the flange. Tension all the reference A bolts to 40% of the requiredapplied bolt stress and check the flange alignment as in 50% tensioning above.Follow this by 70% and 100% tensioning.

Move the tensioners to the reference B, C, and D bolts in turn and tension togive 100% of the applied bolt stress. After each pressurisation, tighten theservice nuts and reduce the pump pressure to zero. Repressurise thetensioners twice to check the tightness of the service nuts.


10/18



PDRP-8440-SP-0011PAGE : 10 of 18

REV : F1


Depending on the actual relaxation of the bolt sets during the above processthe tensioning of sets A, B, C, and D may have to be repeated to obtain aresidual bolt stress within the tolerance specified in section 7.5. It is not arequirement of this standard to check the flange alignment at this stage.




7.5 Checking Completed Joints

On completion of the joint tensioning procedure, the calculated bolt stress shallbe within +/- 10% of the required residual stress for the appropriate materialfrom table 1 unless specified otherwise. (See section 6 for bolt stresscalculation method).

Should the bolt stress be less than the above limits, then increase the hydraulicpump pressure to achieve the applied stress.

For 100% tensioning, tension all bolts using the increased pump pressure. For50% tensioning apply the increased pump pressure to set A followed by set B.Similarly for 25% tensioning apply the pressure to set A followed by B,C and Din order.

The extended bolt threads shall be adequately protected by threaded metalcaps.

The above is additional to a thorough visual inspection based on a goodengineering practice.

8.0 TORQUE TIGHTENING

8.1 General

Accurate torque tightening of a bolted joint is highly dependant on the conditionof the bolting components. In particular, the condition of the threads, matingsurfaces and the type of lubricant applied. For this reason, torque tightening offlanged joints is not preferred practice. However, it is recognised that there maybe circumstances under which torque tightening is necessary. Torquetightening shall be subject to an assembly qualification procedure as describedin section 9.


11/18



PDRP-8440-SP-0011PAGE : 11 of 18

REV : F1


8.2 Torque Tightening Technique

To ensure that consistent torque tightening is achieved, the basic details givenbelow should be followed:-

a) A calibrated torque wrench shall be used.

b) Inspect bolt and nut threads and nut face/flange face for defects.

c) Ensure that nuts run up the bolts freely (by hand) along the workinglength of the bolt.

d) Clean and lubricate all contact parts.

e) Where several joints are being tightened use the same lubricant on each joint.

f) Mark nuts and bolts to give visual indication of nut rotation on the bolt.

g) If a nut seizes on a bolt, replace the nuts and the bolt.

h) Hold torque wrench perpendicular to the flange face or bolt axis, asappropriate.

i) Ensure that the reaction arm is in contact with a rigid support. If reactionis from an adjacent nut ensure that the reaction does not loosen the nut.

j) Sockets shall be checked for cracks, burrs and other defects before use.

8.3 Location of Prepared Bolts

For bolts stress checks, prepared bolts shall be fitted to each flanged joint asshown on Figure 1.

8.4 Torque Values

Table 2 gives guidelines for torque factors for various bolt sizes. Torque factorsare given since the maximum residual stress (table 1) varies with the boltmaterial and joint type. To calculate the required torque, multiply the required

residual stress by the appropriate torque factor. When a torque multiplier isused the torque factors shall be increased to compensate for increased friction(say 10% as a guide).

8.5 Torque Tightening Sequence

The flanged joint shall be tightened using a 40%, 70% and 100% stepprocedure However, the bolts shall be tightened using a 'criss-cross' sequence.Typical sequences are shown in figure 1. Tightening bolts in pairs using twotorque wrenches is good practice.

Complete one round of tightening with the torque wrench set to give 40% of theapplied bolt stress. Check the flange alignment to ensure that the gap is closing

up evenly. Any misalignment up to the limits stated in section 5.3 can becorrected by adjusting individual bolt loads. Misalignments greater than those


12/18



PDRP-8440-SP-0011PAGE : 12 of 18

REV : F1


given in section 5.3 must be investigated and corrective action taken beforeproceeding with the tensioning process.

Increase the torque wrench setting to give 70% of the applied bolt stress andcomplete one round of the flange. Check the flange alignment and correct ifnecessary. Increase the torque wrench setting to give 100% of the applied boltstress and complete one round of the flange.

On completion of the step procedure above, all bolts shall be tightened to thefinal torque working in a clockwise or anticlockwise direction round the flangeuntil no further rotation of the nuts is observed at the required torque.

Ensure that the nuts are rotating on the bolts during the torque tighteningprocedure.

8.6 Checking Completed Joints

The residual bolt stress shall be calculated from the elongation of the preparedbolts (section 6). Because of the effects of friction in the bolting system, theresidual stress may be lower than required for the bolt material (see table 1).

For residual bolt stresses less than 90% of the required value from table 1

estimate the new torque to give 90% residual stress. Apply this torque to allbolts working in a clockwise or anticlockwise direction round the flange.

After achieving a 90% residual stress either on the initial tightening or afterretightening, complete the procedure by tightening in two 5% steps until therequired residual stress is achieved. It is recognised that it is difficult to achievean even bolt stress round a flange using a torque tightening procedure. Avariation of the a final bolt stress of +/- 10% of the required residual stress isacceptable. The above is additional to a thorough visual inspection based ongood engineering practice.

9.0 ASSEMBLY QUALIFICATION PROCEDURE

An assembly qualification for both hydraulic tensioning and torque tightening isrequired. The aim of the qualification is to establish and record the boltelongation, pump pressures and torques by tightening joints under controlledconditions. The recorded data is then used for the subsequent bolting up ofsimilar flanged joints. To qualify a procedure, the procedures outlinedpreviously shall be used with the addition of the following requirements.

a) Qualification of the procedure and the operating crew using a mock upflanged joint is preferred. However, qualification on service joints isacceptable provided that each bolt is accessible for measurement.

b) The procedures previously described shall be used with the additional

requirement that the residual bolt stress in every bolt shall be calculated.

c) A minimum of two joints of each size shall be successfully qualified.


13/18



PDRP-8440-SP-0011PAGE : 13 of 18

REV : F1


d) All bolt sizes to be qualified for torque tightening.

e) Records of bolt elongation, pump pressure and torques, as describedlater, shall be made.

f) The qualification shall be witnessed by specialist group arranged byIOCL.

It should be noted that the successful application of the procedure in the field ishighly dependant on qualification of the procedure and the crew before field joint tightening work commences. It is also strongly recommended that 10% ofthe field joints be checked to ensure compliance with the qualificationprocedure.

10.0 INFORMATION REQUIRED BY A SPECIALIST BOLTING CONTRACTOR

When a specialist bolting Contractor is contracted to carry out joint tightened,the following detailed information shall be provided:-

a) Location of jointName of site

Isometric No.Equipment NO.Tag No/Reference No.

b) Joint DescriptionRatingBolt Size/QuantityBolt & Nut Material SpecificationJoint MaterialResidual Stress (from table 1)Preferred Tightening Procedure(ie tensioning or torque lubricanttype - if specified).

In general, the above information is contained in the line isometric or vesseldrawing and pipeline specifications.

11.0 INFORMATION TO BE PROVIDED BY A SPECIALIST BOLTINGCONTRACTOR (BEFORE WORK COMMENCES)

The following information shall be supplied by the specialist bolting Contractorbefore work begins on the joint. Separate documentation shall be provided foreach joint which shall have a unique identifier.

For a hydraulic tensioning:-


14/18



PDRP-8440-SP-0011PAGE : 14 of 18

REV : F1


a) A written step by step procedure to be complied with during jointtightening.

b) No of tensioning heads to be used (eg 100% or 50%)

c) Head type and size to be used

d) Calculation of bolt elongation required to achieve residual stress.

e) Hydraulic pressure to achieve applied stress.

For torque tightening:-

In addition to the requirements for tensioning above;

a) Type of lubricant to be used (To be checked for compatibility withservices fluid see table 3).

b) Torque requiredc) Coefficient of friction used in calculation

12.0 DOCUMENTATION TO BE PROVIDED BY SPECIALIST BOLTINGCONTRACTOR ON COMPLETION OF WORK

The information given in sections 8 & 9 above shall be included in the finalsigned documentation. A record of the final tightening data shall also beincluded and must contain the following as a minimum requirement:-

a) Assessment of initial condition of the joint

b) Measured elongation of the prepared bolts

c) Hydraulic pump final pressure

d) Hydraulic pump and pressure gauge serial numbers

e) Hydraulic pump and pressure gauge calibration certificates (copies ifnecessary)

f) For torque tightening only, the wrench calibration certificate and finaltorque.

g) Record of initial joint alignment.

h) Record of cleanliness and surface quality checks.

i) Record of lapping checks for Ring Type Joint (RTJ) flanges.


15/18



PDRP-8440-SP-0011PAGE : 15 of 18

REV : F1


FIGURE 1: FLANGE BOLT TIGHTENING SEQUENCE


16/18



PDRP-8440-SP-0011PAGE : 16 of 18

REV : F1


TABLE 1: GUIDE VALUES OF RESIDUAL BOLT STRESSES FOR VARIOUSBOLTING MATERIALS

Guide Values of Residual Bolt Stress for Various Bolting Materials

Spec No Grade Notes N/mm2

A193/BS4882 B7 345

A193/BS4882 B7M 345

A193/BS4882 B16 345

A320 B8M (strain hardened) 170

A320 B8 (strain hardened) 275

A320 L7 345

A193/BS4882 B7/B16 Class 900 Ring Joint 275

Class 1500 Ring Joint 205

Class 2500 Ring Joint 205


17/18



PDRP-8440-SP-0011PAGE : 17 of 18

REV : F1


TABLE 2: SUGGESTED TORQUE FACTORS

SUGGESTED TORQUE FACTORS

Nominal Bolt Dia (in) 40% 70% Final½ 0.10 0.17 0.245/8 0.19 0.33 0.47¾ 0.33 0.58 0.827/8 0.53 0.92 1.311 0.78 1.37 1.951 1/8 1.13 1.98 2.831 ¼ 1.58 2.76 3.951 3/8 2.13 3.72 5.311 ½ 2.79 4.88 6.971 5/8 3.58 6.27 8.961 ¾ 4.49 7.85 11.221 7/8 5.57 9.75 13.92

2 6.78 11.86 16.942 ¼ 9.74 17.04 24.342 ½ 13.46 23.55 33.652 ¾ 18.00 31.50 44.993 23.50 41.13 58.753 ¼ 30.00 52.48 74.963 ½ 37.57 65.76 93.943 ¾ 46.31 81.04 115.774 56.36 98.04 140.91

To obtain torque (N-m) multiply Residual Bolt Stress (N/mm2) from Table 1 by the

above factor.Notes:

1) Calculations are based on well lubricated bolts.2) Assumed coefficient of friction 0.2


18/18



PDRP-8440-SP-0011PAGE : 18 of 18

REV : F1

TABLE 3: ACCEPTABLE LUBRICANTS

1 MOLYSLIP COPASLIP ANTI-SEIZE

2 LOCTITE ANTISEIZE

3 Any other lubricants approved and recommended by IOCL

Documents

Bolt Torque- Foster Wheeler Standard