OIL AND GAS MAINTENANCE

8/7/2019 OIL AND GAS MAINTENANCE

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OIL AND GAS MAINTENANCE

PREPARED BY

SHIEKH MOHD FAIZ (2007241144)


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Introduction

The oil and gas sector has contributed majorly to theglobal economy and has become a sophisticated andcompelling business. This sector comprises only two

thirds of the world's energy but has the capacity todrive the global economy.

The oil and gas industry recruitment opportunities arecountless and a many number of institutes are engagedin seasoning the candidates. This sector is managed

and operated by highly skilled personnel who viewglobal travel as a major part of their profession.


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Scope of maintenance

Actually the maintenance divide to three type.

;-

- Exploration and Production- Refining and Petrochemical

- Transportation and Storage

Focus on maintenance and repair in Oil andGas Pipeline Design.


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Exploration and Production

Contents.

- Repair Strategy

- Replacement

- Grinding Out Defects

- Weld Overlay- Full Encirclement sleeve

- Fillet welded patch

- Flush welded patch

- Welded leak box

- Mechanical clam

- Composite overwrap- Buried pipe rehabilitation

- Brushed and sprayed lining and coating

- Pipe straightening


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Repair Strategy

Addresesses six key decisions.

- Repair techniques

- Materials (chemistry, mechanical properties,corrosion resistance)

- Design (flow and system logic, sizing)

- Fabrication (joining welding heat treatment).

- Examination (NDE of the failed component andthe repair).

- Testing (hydrotest, pneymatic test, leak test


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Replacement

Most common practise for repairing pipe

section

New component or subassembly should fullycomply with the construction code

Important, carefully and clearly specify

lockout, tagout, depressurization, draining and

venting the pipe before cutting or opening the

system.


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Grinding Out Defects

Used when base metal or welds containfabrication or service-included defects, (weldflaws, arc burns, gouges or cracks)

Ground surface is the examined by liquidpenetrant or magnetic particle tto confirmthat the defect has been removed.

The ground out area may be left as-is, withoutweld deposit, if the remaining wall thicknessexceeds the minimum required by code.


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Weld Overlay

Referred to as direct weld deposit.

Consist in depositing weld reinforcement on thesurface of the pipe

Several consideration apply in the selection andapplication of weld overlay repairs

- Compatibility of the weld.

- Sequence of weld bead depostion- Number of passes

- Necessity to minimize residual stresses.


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Weld Overlay


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Full Encirclement Sleeve

A degraded pipe can be repaired with a fullencirclement split sleeve

A type A sleeve (no end closure welds) serves to

reinforce a locally corroded area With a type B sleeve (with the two end clisure

welds) the sleeve serves the same role.

The ends f type A sleeve should be sealed to

avoid corrosion in the pipe-to sleeve annulus. Type B sleeves are used to repair a pipe crack :the crack must be shown to be stable and notable to propagate beyond the sleeve.


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Full Encirclement Sleeve With

Circumferential Weld


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Fillet Welded Patch

Repairs local flaws

Can be circular or square steel patch to the pipe

outer diameter

Common repair technique [API 510, API 570],

except for pipelines where patches are nit use to

pipe sizes 12 and less.

A variation of the fillet welded patch is to repairsmall pitting leak by fillet welding a small bore

fitting (NPS 2 or smaller) to cover the leak


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Fillet Welded Patch


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Flush Welded Patch

Damaged section is cute out of the tank, vessel orpipe and replaced by a section of the same size.

Butt welded flush to the existing pipe

Mostly used for the repair of pressure vessels andtanks, and more rarely for piping with smallerdiameter.

If the patch is rectangular, it should have roundedcorners to reduce stress concentrations.

Post weld heat treatment will be required.


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Flush Welded Patch


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Welded Leak Box

Consist of a pipe jacket with end pieces,placed around the section to be repaired, andseal welded to the pipe

A leak detection drain or pressure gage can beadded to indicate the onset of leakage

The box must be sized to contain the design

pressure of the leaking fluid The stability of a through wall crack should be

analyzed, with adequate safety margins.


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Welded Leak Box


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Mechanical Clamp

A housing comprised of two half shells, with twoend gasket rings.

Tightened against the pipe outer diameter by

bolting Commonly used in power and process pipingsystems.

Certain clamps may be welded to the pipe, in

which case the clamp may be pressure tested andthe welds examined.

Mechanical clamps are also permitted fortemporary repair of nuclear power plant


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Mechanical Clamp


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Composite Overwrap

A repair technique for corroded or dented pipes

or pipelines that does not require welding

Some follow the same principle as a type a full

encirclement sleeve

Objective is to reinforce the corroded wall this

avoiding outward bulging of the pipe wall

Other overwrap sleeves: a resin impregnatedfiber glass is wrapped by hand several times

around the leaking pipe.


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Composite Overwrap

Ductile Burst is Preceded by Outward Bulging


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Buried Pipe Rehabilitation

Repair buried pipe without the costly effort ofdigging, has resulted in the development ofseveral trenchless repair techniques.

Accomplished by inserting a chemically resistanthigh density polyethylene (HDPE) pipe inside theexisting degraded pipe

The HDPE line is first deformed into a U-shape,and pulled through the existing pipe.

The U-shaped liner is then reformed to its circularshape, forming a pipe within a pipe.

The choice of the liner material is important.


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Buried Pipe Rehabilition


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Pipe Splitting With Polyethylene Pipe

Follower


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Brushed and Sprayed Lining and

Coating

A number of linings (covering the inner diameter)

and coating (covering the outer diameter) can be

rolled, brushed and sprayed on the pipe to stop

erosion, corrosion or abrasion of the pipe wall.

Linings are factory applied on new pipes or

applied in the field.

If the degradation is due to aggressive abrasion ofthe inner diameter, a ceramic reinforced epoxy

liner may be used.


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Pipe Straightening

Used to replace an accidentally bent pipe

Precaution:

Should not use dent or gouge

Pipe cross section should not ovalize more thanpermitted in the construction code.


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Summary

Pipeline rehabilitation and repair is essential forpipeline service

Techniques depends on type of defects and the

services of the line Cautions should be taken and risk have to be

assessed before repair carried pit

Repairing berried pipeline is costly and needcaution

Pipe straightening is used to repair bend pipes.


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Offshore Riser Pipeline Repair

Without Underwater Welding


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Referrence

youtube.com

wikipedia.en

pipelineengineering.com cycla.com/opsiswc/docs/S8/P0054/IMP021201Re

search

ogmtna.com/index.html

http://solutions.3m.com/wps/portal/3M/en_US/

Oil-Gas/Home/Solutions/Exploration-Production/

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OIL AND GAS MAINTENANCE