Presentation Hot Tapping

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HOT TAPPING:What does the Procedure say?

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International Definition:

Hot Tapping:

“Hot Tapping is the precise process of drilling a hole in an on-stream operational piping system without spilling its contents or interrupting its flow.”

or in practical terms“Hot Tapping is a means by which access is made to the inside of an operational pipeline, using either a drill or a circular cutter.”

Hot Tap Applications include:

•Attachment of a branch connection to the line, •Installation of an internal probe or monitor, •To stop or redirect flow in a line for maintenance or repair purposes.•Implies positioning a branch fitting on an operating pressurised line, flowing or stagnant. Followed by cutting a hole in the header through the branch to allow connection to the flowing media. Normally implies using a welded fitting,

•Can also be applied as a repair method to remove defects, i.e. dents.

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Factors, which govern standard, hot tapping a) Size on size hot taps is not permitted. The size of the hot tap branch shall be limited to a maximum of two pipe sizes smaller than the header size. b) Hot tapping nearer than 460 mm to flange or threaded connection or approximately 70 mm to a weld seam should be avoided. c) Hot taps shall not be made on circumferential or longitudinal welds. d) A hot tap shall not be made on the radius of any fitting.

e) Tie-ins with a bore of more than one-half the header shall require the use of a split tee (full encirclement fitting). Those on one half the headers bore or smaller shall be an integrally reinforced branch fitting, e.g. a weldolet or saddle type sweepolet whenever reinforcing is required. f) Some of the older hot tap equipment only allows hot tapping to be performed in the vertical up and down position. Enough free space with no obstruction above the pipe to be tapped shall be provided in these cases. Modern hot tapping machines do not have this restriction.

Extract from SASOL SGR-MOR-000011

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HOT TAPPING

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Hot tap Configuration

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Non Standard Taps

Off-Set TapAngle Tap

Bend Tap

Blind Tap

Inverted Tap

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Hot Tap OrientationStandard vertical tap - no unusual problems

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Angled vertical tap - no problems for angles less than 45 degrees

Hot Tap Orientation

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As the angle of tap rotates around there becomes more chance of the swarf from the tap coming back towards the valve and the tapping machine adapter resulting in problems closing the valve and withdrawing the cutter fully.

Hot Tap Orientation

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As the angle of tap rotates around there becomes more chance of the swarf from the tap coming back towards the valve and the tapping machine adapter resulting in problems closing the valve and withdrawing the cutter fully.

Hot Tap Orientation

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The measuring rod will tend to fall out. It is also considerably harder to install the drilling machine into position.

Hot Tap Orientation

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Clearance for Hot Tap

Longitudinal weld accessrestricted by adjacent

pipes

Longitudinal weld location at an alternative position in order to improve

weld access 12

Hot Tap Fittings

Hot Tap fittings are either bolted or welded to the header pipe line. Atapping/drilling machine is attached to the valve, which is attached to the hot tap fitting. A cutter, attached to the tapping machine is inserted into the hot tap fitting through the valve and the tap is made. In the case of a permanent valve, a branch connectioncan be made, allowing flow through the outlet.

Rules of Thumb:

For reduced-branch taps, weldneck flanges on a weld-o-let can be used, but the size of the branch must not exceed 50% of the header diameter, to ensure remaining strength is not compromised.Where the branch will exceed 50% of the header diameter, Hot Tap fittings are full-branch or reduced-branch split tees, designed for use with Tapping Machines.

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Fabrication

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Fit up of split tee for AIA inspection before welding

Spit tee being machined to clients specification

12” #600 Line Stop valve being pressure tested.

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Fabrication & Test Plan

HOT TAP - CLASS 150

Compliance to ISO 9001: 2008

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CST29 Drilling Machine

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Hot Tap Fittings

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Hot Tap Fittings:

Are equipped with ANSI Class 150, 300, 600, 900 or 1500 (SI PN 20, 50, 100, 150 or 250) weld neck RF or RTJ flanges.

The reduced-branch split tee fittings can also be furnished with “Completion-plug” flanges for use as bypass fittings. Full-branch fittings are available in 2" - 60"(63mm-1,500 mm).

Reduced-branch fittings are available in any size or pressure configuration to meet customer needs.Plugging (Stopple) Fittings allow a means of isolating the flow in apiping system for repair, maintenance or pipe relocation activities,by incorporating a completion plug inside the flange on the branch.

The only real difference between a hot tap and line stop split tee fitting is mostly the use of a “completion plug” flange in the neck of the line stop fitting.

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On Site Welding

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In-Service Welding for Hot Taps:

Welding onto an in-service piping system requires specially qualified welding procedures and trained personnel.

The main concerns for in-service welding are:•Burn through•Hydrogen Cracking of Fillet Welds•Chemical Reactions from Heat

With modern day low hydrogen welding techniques and properly qualifiedprocedures and welders, the above are not normally a concern, within tested limits.

In practice pipe wall thickness' down to 4mm (0.156") have been successfully welded in-service, with the appropriate procedures, and in special circumferences 3mm (0.125”). However, the normally accepted practical minimum is 4.8 mm (0.188”).

On pipelines the weld procedure and welding qualification includes theprovision for qualification and testing with highest expected rate of heatloss, or restraint levels, and maximum carbon equivalent of the materials tobe welding.

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In-Service Welding for Hot Taps (Continued):

Pipeline fittings are also normally also required to meet the CSA Z245.11 Steel fittings & CSA Z245.12 Steel flanges codes, where applicable. These specifications imply that all welds must be to ASME IX and subject 100% radiography to, ASME acceptance criteria.

On pressure piping systems (i.e. ASME B31.3 & ASME B31.1) there is no code, or regulatory requirement to consider any in-service welding consideration. It was highly recommended that ASME IX welding qualifications be supplemented by API recommended Practice 1107 for maintenance, however, API 1107 was due to be replaced by Appendix B in API 1104.

API 570 :Requires that all repairs and alterations to the piping system must be done by anorganisation acceptable to the jurisdiction and must be authorized by theinspector prior to its commencement.

All repairs and welding shall be done in accordance to the principles of ASME B31.3, or the code to which the piping system was built.

Any welding on piping components must be done in accordance with API Recommended Practice 2201, Procedures for Welding or Hot Tapping on Equipment Containing Flammable or combustible liquids.

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In-Service Welding for Hot Taps (Continued):

API 2201 specifically indicates that ASME IX does not cover in-service welding conditions and that API 1107 should be used to qualify both welding procedures and welders on pipe containing flammable or combustible liquids.

In addition, API 570 requires that the inspector shall use, as a minimum the "Suggested Hot Tap Checklist" contained in API 2201 for hot tapping performed on piping components.

API 2201 requires:In advance of "hot tap" work the following should be prepared:•A detailed in-service welding procedure.•A hot-tap procedure.•A connection design.•Health, safety, fire protection, and other appropriate instructions.

*Always verify the header pipe wall thickness prior to in-service welding.

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Welding Sequence of Split Tee Fitting (Split Sleeves):

Sequence of welding is important. Weld the longitudinal-type seams of full-encirclement fittings first. If factors permit, weld both longitudinal-seams simultaneously. Should factors prohibit this, alternate side-to-side to avoid excessive distortion.

Do not weld both circumferential-type seams simultaneously. This may introduce excessive stresses into the fitting and piping system.

Longitudinal- seams should never be welded to the header/carrier pipe.

Where a full penetration longitudinal weld is desired, the use of a Backing Strip is strongly recommended, which should be specified when doing the design.

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Pressure Testing

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Pressure Testing of a Hot Tap Fitting or Split tee:

Prior to tapping the fitting should be pressure or leak tested. The pressure, or leak test, will subject the header pipe wall to an external pressure. The intention of the appropriate design code requirement may be for the hot tapping/line stop fittings to be internally pressure tested .Exceeding the piping system internal pressure may cause damage to the header pipe, making it difficult or impossible to complete the hot tapping and/or line stop operation, thereby compromising the integrity of the piping system . The allowed safe external test pressure depends on :

•The header (carrier) pipe diameter to thickness ratio, •Grade of material, •Roundness of the pipe •Local wall thickness loss•Corrosion•Mechanical damage, should also be a consideration.

*ASME VIII external pressures design principles can be applied, but there is a need to consider local deformation as well, which may result in causing a dent on the header pipe at the fitting branch opening location, during the pressure test.

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Quality Management System: On Site - Inspection, Preparation, Works Instruction, Log Sheet

Hot Tapping and Linestopping

         Tapping Machine Ser. No.  

Class Rating  

Size  

Date of Last Service  

EQUIPMENT CHECKLIST

Sequence TAPPING MACHINETick Applicable

YES NO N /A

  Do You have a Job Card? If not, get one before proceeding

  Is there a Green Ticket and Pressure Test Certificate?      

  If NO, pressure test the assembly first before proceeding 1Enough head Room above the tap for the tapping machine      

2Enough travel for completing the Hot Tap      

3Correct Tapping adapter fitted      

4All bolts/ threads fastened      

5Enough travel for completing the tap      

6Correct Tapping adapter selected      

7Tapping adapter aligned with cutter in center of adapter      

8Correct Pilot installed      

9Catch wires move freely on pilot      

10At least two catch wires will catch coupon      

11Correct Cutter Selected      

12Cutter teeth in good condition      

13Cutter Holder secured to cutter    

14Pilot secured to cutter Holder    

15Pilot retracts into tapping adapter      

16Tapping Dimensions taken and recorded      

17Completion Plug setting distances taken and recorded      

18No openings to atmosphere for accidental product release      

19Bleeder Valve Correct Pressure rating      

ALL C.S.T. HOT TAPPING

IS DONE AGAINST A QUALITY CONTROL

PLAN

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Hot Tap Animation

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Coupon retainedby ‘U’ Wire

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Coupon retainedby ‘U’ Wire

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Coupon and cutterare withdrawn

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Vent offProduct

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Productcleared

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Thank You