Hot Tappings

8/6/2019 Hot Tappings

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CHAPTER 2

Hot Tapping

Standard 806Rev 0

June 2000Page 1 / 13

CONTENTS

1 PURPOSE

2 RESPONSIBLE PERSONS

2.1 FIELD SUPERINTENDENT

2.2 SAFETY SUPERINTENDENT / AUTHORITY2.3 PLANT MANAGER (Halliburton)2.4 CONSTRUCTION SUPERVISOR

3 PROCEDURES

3.1 GENERAL3.2 WELDING3.3 TANKS3.4 CHECKS AND CONDITIONS BEFORE WELDING3.5 CHECKS AND CONDITIONS AFTER WELDING3.6 CHECKS AND CONDITIONS BEFORE CUTTING3.7 CHECKS AND CONDITIONS AFTER CUTTING

REFERENCES

APPENDIX HOT TAPPING FORMS - CHECK LISTS


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HOT TAPPING

1. PURPOSE

To ensure the safety of personnel, plant and equipment during Hot Tapping operations.

N.B. : Hot Tapping should be avoided, if possible, unless it is proved not to be practical toisolate the plant & perform the work under isolated conditions.

2. RESPONSIBLE PERSONS

2.1 FIELD SUPERINTENDENTThe Field Superintendentis responsible for :-

Assessing the need, and granting permission for Hot Tapping to be carried out.

2.2 SAFETY SUPERINTENDENT /AUTHORITY

The Safety Superintendent/Authority is responsible for :-

Monitoring the safety of all working practices.

Completing Section 2 of the Hot Tapping Form (Refer to Appendix).

Witnessing the Hot Tapping procedure and ensuring that all safetyrequirements have been met before work commences and that adequate fireappliances are available at the work site.

2.3 PLANT MANAGER

The Plant Manager is responsible for :-

Ensuring process conditions are suitable throughout the task.

Completion Section 3 of the Hot Tapping (Refer to Appendix 1).

Maintaining communications with the Construction Supervisor, and theControl Room throughout the operation.

Issuing a Valid Main Work Permit (Hot).

2.4 CONSTRUCTION SUPERVISOR

The Construction Supervisor is responsible for :-

Ensuring that the requirements of the Work Permit are carried out.

Familiarising himself and his operators, with the details of the overallprocedure, including :-

The Welding Procedures. The Tapping Procedure. All Safety and Emergency Procedures.

Completing Section 1 and Section 4 of the Hot Tapping Form (Refer toAppendix).

Ensuring that due care and attention is maintained throughout the operation.

3. PROCEDURES


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Hot Tapping

Standard 806Rev 0


3.1 GENERAL

"Hot" or Pressure Tapping is used to connect pipes and vessels without removing

them from service. This method is only used when no other suitable means ofaccomplishing the objective is available. Normally, TEPR will engage specialistcontractors to carry out this task, but all personnel concerned should be aware of theprecautions to be taken which are :-

All Hot Tapping work must be conducted under conditions of the WorkPermit System (Standard 601) and the conditions of such permitsmust be strictly adhered to.

A Production Operator must be present during Hot Tapping work.

A Safety Officer must continuously monitor the task.

Communications must be established with the Site Control Room to

ensure process conditions are suitable prior to and during Hot Tapoperations.

All welding, heat treatment, NDT and cutting processes are to beapproved by the Inspection Engineer.

All welds must be completed by a welder qualified to undertake theprocedure. Qualifications should be generally as per ASME Code orapproved local Standard requirements having regard for the specificrequirements of the Hot Tap.

Hot Tapping normally involves two distinct stages :-

Welding on an appropriate T-piece or similar fitting.

Cutting through the pressure envelope using a specialised cutting toolmounted on the fitting.

Some equipment is unsuitable for Hot Tapping because of metallurgy, thickness ofmetal, or stress relieving. Hot Tap fitting and weld rod metallurgy must be compatiblewith equipment, piping, vessels, etc. to be tapped.

Hot Tapping MUST NOT be performed on equipment that contains :-

Hydrogen or hydrogen mixtures, where the possibility of hydrogenabsorption of the metal exists.

Flammable vapour/air or oxygen mixtures where the possibility existsof the mixture being within the flammable or explosive range.

Chemicals, such as acids and chlorides, which are likely todecompose and become hazardous due to the heat of welding.

Caustic solutions or amines, if the concentration and temperature aresuch that the fabrication specification calls for stress relieving tocontrol the possibility of stress corrosion cracking.

Unsaturated hydrocarbons, especially ethylene, unless evidenceprecludes the possibility of explosive decomposition of the materialunder initiation of the welding hot spot.

Cladding or linings, such as glass, lead, refractory, plastic, strip lining,etc.

Hot Tapping must also be avoided upstream of rotating equipment unless suchequipment is protected from the cuttings by means of filters or traps.


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Hot Tapping

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Taps should not normally penetrate existing welds, or other discontinuities. For steelsin particular, local toughness variations should be considered. Generally taps shouldnot be closer than 46 cm (18 inches) to a flange or threaded connection and 7.5 cm

(3 inches) to a welded seam.

No attempt must be made to Hot Tap atmospheric pressure petroleum storage tanksnear to or above liquid level because of the danger of an explosive atmosphereinside the tank. A thorough and complete inspection of each connection locationmust be made to verify that the metal thickness is adequate for the pressure andtemperature involved and that the area is free from internal defects, particularlylaminations.

Some flow is desirable in pipework etc. during hot tapping to prevent overheating ofthe liquid etc. High flow rates should be avoided. In certain cases where there maybe insufficient or interrupted flow, such as flare lines, it may be necessary to

continually purge or flood the line with steam, inert gas or hydrocarbon gas to ensurethat the line or equipment does not contain a flammable mixture during the weldingoperation.

The connection through which the Hot Tap is to be made must be designed toaccommodate not only the machine but there must also be sufficient clearance for itsoperation.

In all cases where welding is involved, a detailed and specific study must be made ofthe metallurgy requirements. Normally welding procedures based on, e.g. ASMESection 9, BS 4870, etc., will generally not be suitable for Hot Tapping fittings withoutprocedural modifications. These codes are intended for shop fabrication of new

equipment and are NOT directly applicable to welds made on live lines.

It will normally be necessary to undertake a comprehensive simulation of the Hot Tapin order to qualify the weld procedure. The simulation must duplicate the thermal andpressure conditions of the final weld. These procedures are intended as a generalguidance only. A detailed written procedure approved by the Head of Inspection mustbe prepared for each specific Hot Tapping operation, identifying as a minimum:-

Pipe/vessel material specification and wall thickness. Contents. Required process conditions. Qualified Welding Procedures. Welding equipment / consumables. Emergency procedures. All equipment necessary to complete the work. Site NDT Procedure & acceptance standards (inc. pressure tests).

3.2 WELDING

Ultrasonic checks must be conducted to ensure that there is a minimum thickness of6.4 mm, and that the metal is free from laminations or other defects. Hot Taps mustonly be made in lamination free areas.

To minimise the possibility of burn-through the first weld pass to the equipmentshould be made with a 2.4 mm (3/32 inch) diameter welding electrode. If the actualmetal thickness does not exceed 12.8 mm (1/2 inch) the remaining passes should bemade with electrodes not exceeding 3.2 mm (1/8 inch) diameter.


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Hot Tapping

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For heavier thicknesses, where burn-through is not a primary concern, largerdiameter electrodes may be used to compensate for the larger mass. This willminimise the potential for fusion defects.

3.3 TANKS

Tanks must never be filled or emptied while hot work is in progress.

Valves on liquid lines to the tank must be closed, tagged and locked, or otherwiserendered inoperative.

All heating coils within the tank must normally be turned off and isolated. However,each case must be individually reviewed in relation to the tank content.

A one metre head of liquid must be maintained above the hot work area when

welding or Hot Tapping is being done.

A hand gauge measure of the tank contents should be made since automatic orremote reading gauges may not be reliable enough for this measurement.

3.4 CHECKS AND CONDITIONS BEFORE WELDING

Before proceeding with the weld, the following checks and conditions must besatisfied :-

The welding procedure must be reviewed with all involved personnelto ensure all requirements can be precisely complied with.

The tap location must be verified, unambiguously marked, andinspected for integrity.

A valid Main Work Permit (Hot) has been issued and all necessarygas tests have been made to ensure a safe environment.

A dry chemical fire extinguisher must be provided and a fire hose mustbe run out and pressurised.

A fire watch must be established, the area must be cordoned off and warning noticesposted.

The precautions of welding of the fitting must be in accordance with Standard 804 -

Welding and Burning.

Care must be exercised to see that the fitting is properly positionedbefore welding, so that misalignment of the hot tap machine does notoccur.

Preheating requirements for live process equipment must generally besubject to special consideration, as they will differ from those requiredfor the same material under normal workshop conditions.

When metal temperatures are below atmosphere dew point,preheating or other steps may be desirable to reduce moisture contentin the weld area.

3.5 CHECKS AND CONDITIONS AFTER WELDING

Before any post weld procedures are carried out, check the tightness of the bolts,packing, packing nuts and by-pass lines to avoid possible leakage :-


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If the temperature/pressure of the line or vessel will permit, ahydrostatic test should be conducted in accordance with Standard 605Pressure Testing. Buckling of the pipe should be considered.

Subject to engineering approval a helium nitrogen leak test mixture,together with a mass spectrometer can be substituted for thehydrostatic test.

Additional testing, such as radiography, dye penetrant, ultrasonic ormagnetic particle may be required, particularly on the first pass andfinal weld, to check for underbead cracking. Care must be taken tothoroughly clean the weld area of any foreign material or residues ifthese tests are to be performed after the first pass. These additionalprocedures should not be relied upon to replace hydrostatic orpneumatic testing.

3.6 CHECKS AND CONDITIONS BEFORE CUTTING

On installation of the machine the manufacturer's instructions must be strictlyadhered to, and the following items checked :-

Ensure the gate valve on the connection nozzle is clean, fully opensand closes, and is centred on the flange.

The boring bar must be run through the main valve opening severaltimes to be sure the cutter does not jam or drag.

Calculate the travel of the cutter to ensure that it can be retractedthrough the valve, particularly in small size pipe, and to ensure thatthe opposite side of the pipe is not cut.

Check the bleed-off valve holds pressure, and is not plugged.

Check the possibility need for support the cutting machine to preventunacceptable bending moments due to its size. Also consider thepossibility of line distortion due to the machine's weight.

3.7 CHECKS AND CONDITIONS AFTER CUTTING

The manufacturer's instructions must be followed when retracting the bore andclosing the valve.

If the blank or coupon is lost, no attempt should be made to fish for it. In some casesit may be necessary to shut down the equipment and depressurise the line to recoverthe blank.

REFERENCES

HS (G) 5 Health and Safety Guidance Booklet. Hot Work : Welding and CuttingEquipment Containing Flammable Materials.

API 2201 Procedures for Welding and Hot Tapping Equipment ContainingFlammable Materials.


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Hot Tapping

Standard 806Rev 0


APPENDIX

HOT TAPPING FORMS - CHECK LISTS

Before any Hot Tap operation, it is essential that all engineering and safety considerationshave been made to protect personnel and plant.

It is mandatory to complete the attached Hot Tapping Procedure Forms before each HotTap.

The following sections must be completed and signed by the "Responsible Persons" beforethe operation commences.

SECTION 1 TO BE COMPLETED BY THE CONSTRUCTION SUPERVISOR

PIPELINE DATA

Diameter .............................................

Specification .............................................

Wall Thickness .............................................

Product(Normally/During Tapping) .............................................

Pressure(Normal/During Tapping) .............................................

Temperature(Normal/During Tapping) .............................................

Location of Hot Tap .............................................

Condition(As Welded/Stress Relieved) .............................................

HOT TAP DATA

Number off .............................................

Size (Run and Branch) .............................................

Flange Rating .............................................

Valve Type .............................................

Inner Diameter of Fitting .............................................

Type of Tap .............................................

Hand/Air/Hydraulic .............................................


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Name of Contractor .............................................

Name of Operator .............................................

Why is not practicable to shut down the vessel /pipework & perform the work under isolated / inertedconditions ? ..............................................

SECTION 1 (CONTD) GENERAL CONSIDERATIONS

NOTE : This is a guidance check list. Generally no Hot Tap should proceed unlessthe "normal" requirement can be met.

Normal

Requirement

1. Has area to be welded been inspectedfor thickness and freedom from laminations ? ....................................... (YES)

2. Can any requirement for stress relieving the weldedarea be met ? ........................................ (YES)

3. Do the flanges, bolts, gasket, pipe to be installed meetthe piping code for the line or vessel to be Hot Tapped ?................................. (YES)

4. Does the chemical composition of the contents in the

line or vessel affect metal strength when material iswelded ? ........................................ (NO)

5. Does the vessel or line contain hydrogen or flammablemixtures ? ........................................ (NO)

6. Is the material in the line stable under heated conditions,and free from oxygen ? ........................................ (YES)

7. Can any specified preheat of the weld area bemaintained ? ........................................ (YES)

8. Is there clearance to accommodate the operationof the Hot Tap machine, and is there sufficientclearance to retract the cutter through the valve ? ........................................ (YES)

9. Is the Hot Tap fitting of proper length to accommodateoperation of the Hot Tap machine ? ........................................ (YES)

10. Is the area to be Hot Tapped located below the liquidlevel of a tank or on a line or piece of equipmentin which fluid flow is established ? ........................................ (YES)

11. Is a company or contact welder being used ? ........................................

12. If contract, contract number ? ........................................

13. Have specific welding procedures been formulated ?........................................ (YES)


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14. Has the operator been assessed with respect to hiscompetence in Hot Tapping? ....................................... (YES)

15. Have these welding procedures been approved byHead of Maintenance ? ........................................ (YES)

16. Is the Hot Tap location at least 18" away from acircumferetial weld or fitting and 3" away from alongitudinal weld? ........................................ (YES)

17. Do we have the correct welding equipment for the jobas specified in the Weld Procedure Specifications ? ........................................ (YES)

18. Have specific heat treatment procedures as definedin the Weld Procedure Specification been approved by

Head of Inspection ? ........................................ (YES)

19. Have NDT procedures been adequately defined andapproved by Head of Inspection ? ........................................ (YES)

20. Has a full simulation been conducted ? ........................................ (YES)

21. Are process conditions suitable for Hot Tap operation ?.................................. (YES)

22. If process conditions are not suitable, what conditionsare required to enable safe and correct completion ?........................................

23. Would an ESD, and loss of product flow jeopardisesafety or welding standards ? ........................................ (NO)

OTHER CONSIDERATIONS

SIGNED :.......................................................................

CONSTRUCTION SUPERVISOR


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SECTION 2 SAFETY SUPERINTENDENT / AUTHORITY

NormalRequirement

1. Have combustible and/or toxic gas sets been conductedin the area of Hot Tapping ? ........................................ (YES)

2. Has fire fighting equipment been properly provided andcorrectly located ? Is a fire hose run out andpressurised ? ........................................ (YES)

3. Is protective equipment necessary in the Hot Tappingarea ? If so, has it been provided ? ........................................ (YES)

4. Are emergency procedures necessary ? If so, what arethey ? ........................................

5. Have all personnel been briefed as to the precautionsand emergency procedures ? ....................................... (YES)

6. Is all equipment required suitable for hazardous areas ?................................. (YES)


SIGNED :......................................................................

SAFETY SUPERINTENDENT / AUTHORITY


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SECTION 3 PLANT MANAGER

NormalRequirement

1. If process conditions requested are other than normal(Section 1, Item 21) do these changes put limitationson systems or plant ? ........................................

2. Has a valid Main Work Permit (Hot) been issued ? ........................................ (YES)

3. Have communications been set up with TaskSupervisor and Control Room ? ........................................ (YES)

4. Can specified Hot Tap conditions be maintained forthe full duration of the welding/tapping operation ? ........................................ (YES)


SIGNED :......................................................................

PLANT MANAGER


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SECTION 4 CONSTRUCTION SUPERVISOR

NormalRequirement

1. Have all Work Permit requirements been met ? ....................................... (YES)

2. Does Hot Tapping machine have a suitable pressureand temperature rating for this job ? ....................................... (YES)

3. Is the fitting properly positioned so that misalignmentof the Hot Tap machine will not occur ? ....................................... (YES)

4. Is scaffolding necessary ? .......................................


SIGNED :......................................................................

CONSTRUCTION SUPERVISOR

Hot Tappings

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