hot tap and temper bead

[arvinda shan]

Dear all,

 

What is the relation between temper bead and hot tapping? Is there any specific procedure to qualify for hot tapping or only welders to qualify downhill progression?

 

arvinda

 

 

[Declan Foley]

Arvinda,

No relationship.....temper bead is a welding process.........hot-tapping
is a mechanical process, which involves drilling into a vessel or pipeline!

temper bead is the welding process usually ( but not always ) employed
when welding the hot tap fittings (usually weldolets, split tee's
etc....) onto the vessel or pipeline as part of the hot tap process.

As regards qualifying welders, you should be very careful here, because
depending on service, this can be a hugely critical operation, and doing
it wrong can have catastrophic results. Its a while since I have done
any but as far as I can remember the best specs are British Gas (
Transco ) PS-P2 & PS-P9

regards

Declan

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[arvinda shan]

Thanks for your response.

 

One more clarification. In our project, for hot tapping activities, split tee welding is going on with out any procedure qualification. As per sec IX QW290.4 , fluid backing, heat input etc... are essential for temper bead welding. For that essential variables no PQR has been qualified.Need separate procedure for doing these activities or no need? Plz clarify.

[Eduardo Calva]

Can anybody tell me which are the variables to take in account in order to qualify a WPS for hot tap?, I mean, is it just diameter, thickness, material spec., ?, or do I have to take account temperature, flow, fliud characteristics?
 
Another question is:  Can I use a old WPS for HT used in other projects?

Eduardo Calva

 

[Karthik]

Hi, For WPS fluid ets.,are all no need. You can use your old WPS.But you check with the old WPS range and qualifications to your current project.If it suits..then go ahead. Karthikeyan.S QA/QC Manager Getabec Energy Co.,Ltd. 379,Moo6,Soi8,Nikhomphatana, Rayong-21180, Thailand. Phone: 0066 38 897035-8 (Off) Fax: 0066 38 897034 Hand Phone: 0066 892512282 --- On Mon, 10/4/10, Eduardo Calva <eduard...@hotmail.com> wrote:

[Declan Foley]

Arvinda,

I don't have a copy of spec here, so am not sure. The fact that you are putting a split tee on means that it is a reasonable size hot tap. If you are doing this with no procedure, might I recommend that you not stand too close to this when they retract the drill, particularly if this is a lethal or explosive service............

Declan

[Geoff]

A good standard to read is API 1104 appendix B.  It covers that most important variables for hot tap welding procedures.  The most important variables are flow condition, fluid type, and material chemistry.  There are others than are essential variables and it is best to read appendix B.

--

[agme...@cantv.net]

Hi Eduardo,
I understand that you make a ht, you must perform the calculations as indicated in API RECOMMENDED PRACTICE 2201.
Your wps may be applicable to the type of joint requerimietnos, base material, etc.

To your second question, yes, clear the considerations that you recommended API noted above.

Kind Regards,,
A. Gustavo Mendoza

oct 4, 2010 03:20:12 AM, material...@googlegroups.com wrote:

===========================================

[arvinda shan]

Mr.Geoff,

 

We can refer API1104 App.B if its OFF PLOT. Suppose for ON PLOT, the hot tapping activities, which is the reference document for  procedure qualification and mechanical testing. Because in some projects for hot tapping activities, they made separate procedures and some projects with out qualifying, using existing WPS. Plz. clarify.

 

arvinda

[pgoswami]

Hi Arvinda,

 

What's the service environment gaseous /flammable liquid or gases or any chemicals or steam/water. What's the design code of the component which is to be repaired by Temper bead welding technique.

 

Welding is only a part of the hot tapping process. There are two established guidelines in the industry for hot tapping :-

1. API-RP-2201-Mostly used for hot tap on oil and gas pipelines.
2. ASME PCC-2- provides methods for repair of equipment and piping and vessels within the scope of ASME Pressure Technology Codes and Standards after it has been placed in service.These repair methods include relevant design, fabrication, examination, and testing practices and may be temporary or permanent, depending on the circumstances.As per PCC-2, Hot Tap on pipelines shall be done to API RP-22.Temper bead weld repair is accepted by this document. Note API-510 also accepts temper bead weld repair, but subject to the verifications of operating media, not across the board. 01

One has to qualify a temper bead repair technique with the guidelines of QW-290(Sec-IX).Follow the guidelines of QW-290.4 to establish the welding procedures. For meaningful temper bead weld repair a PQR shall be qualified under simulated conditions, worst condition would be more proven. Temperbead welding  is a substitute for PWHT, hence it's a serious issue.

 

 

Thanks.

 

 

Pradip Goswami,P.Eng.

Welding & Metallurgical Engineer/Specialist

Email-pgoswami@sympatico.ca,

pgos...@quickclic.net

 

---

From: material...@googlegroups.com [mailto:material...@googlegroups.com] On Behalf Of Declan Foley
Sent: Monday, October 04, 2010 6:22 AM
To: material...@googlegroups.com
Subject: Re: [MW:7350] hot tap and temper bead

[limesh M]

Dear Arvinda,

Pradip Sir, explained it very well.Temper bead is the technique normally using during split tee welding to the run pipe before drilling(hot tapping). Temper bead technique is prefered to deposit weld metal so that we can avoid PWHT.However we have to check the hardness of the weld metal and make sure that it is with in the acceptable limit.It is a critical process and separate procedure required for welding of split tee and repair of split tee weld.If it is a pipeline, PQR normally qualified based on API 1104 Appendix B and API 1107. Two longitudinal and two circumferential welds are required to complete split tee welding.one longitudinal weld normally completed by two welders and opposite side completed by another two welders. Welding normally starting from center of the grove and proceed to the end(One welder from center to left end and another center to right end).Normal case ,backing strip used in between the split tee groove and run pipe to avoid the direct contact of the weld metal to the run pipe.Each pass shall be monitored carefully and make sure that all the welding parameters are with in the acceptable range of approved welding procedure specification.  Circumferrential weld also executed by using two welders at the same time.Two buttering layers normally applied to the run pipe surface before starting the circumferential welding .Low hydrogen electrodes are prefered to avoid HIC.Before starting any activity ,we have to measure the thickness of the hot tap location/split tee welding location, inside fluid pressure,fluid flow rate(every operating company have their own norms to asses this values).If these are all with in the safer side ,then only we are authorised to touch the pipe.

 

 

 

 

Regards,

 

Limesh