RE: 225] RE: 224] RE: 213] RE: 206] PWHT for joint of two differentthk - 43 mm to 36mm

[Bathula Raghuram (Mumbai - PIPING)]

Yes you are correct for the piping, but the subject discussion was for a pressure vessel designed as per ASME Sec VIII div1.

 

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From: material...@googlegroups.com [mailto:material...@googlegroups.com] On Behalf Of Ranasaria Shivanand Rajendra
Sent: Thursday, September 13, 2007 4:58 PM
To: material...@googlegroups.com
Subject: [MW:225] RE: 224] RE: 213] RE: 206] PWHT for joint of two differentthk - 43 mm to 36mm

 

Hi Gents,

 

I feel the criteria mentioned in e-mail below, may not be true for Process Piping ( as per ASME B31.3).

 

As per ASME B31.3 Clause 331.1.3, PWHT is required for Thickness > 19 mm.

For connection of two pipes of different thickness, higher thickness of the two pipes should be considered for PWHT of the joint.

 

If anyone feels otherwise,  please comment.

 

Also it may be noted that there are a little different criteria applicable for branch welds covered in clause 331.1.3a.

 

Regards,

Rana

Shivanand R Ranasaria

Contact +971 2 502 2058

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From: material...@googlegroups.com [mailto:material...@googlegroups.com] On Behalf Of Bathula Raghuram (Mumbai - PIPING)
Sent: Thursday, September 13, 2007 9:46 AM
To: material...@googlegroups.com
Subject: [MW:224] RE: 213] RE: 206] PWHT for joint of two different thk - 43 mm to 36mm

 

However I forgot to mention, Welds on Dished end (by seeing the dia it is not seamless) and attachment (nozzles), if any could require PWHT.

 

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From: material...@googlegroups.com [mailto:material...@googlegroups.com] On Behalf Of Bathula Raghuram (Mumbai - PIPING)
Sent: Monday, September 10, 2007 9:18 AM
To: material...@googlegroups.com
Subject: [MW:213] RE: 206] PWHT for joint of two deifferent thk - 43 mm to 36mm

 

See UW-40(f) (5) (a)

When a welded joint connects parts of unequal thicknesses, the nominal thickness is the thinner of two adjacent butt-welded parts including head to shell connections.

Hence PWHT is not required required for this joint, but Preheat shall be maintained @ 95 deg.C.

 

Raghuram Bathula

 

 

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From: material...@googlegroups.com [mailto:material...@googlegroups.com] On Behalf Of Agrawal Sunil (Mumbai -Stequ)
Sent: Saturday, September 08, 2007 12:39 PM
To: material...@googlegroups.com
Subject: [MW:206] PWHT for joint of two deifferent thk - 43 mm to 36 mm

 

My equipment is having the following condition:

 

MOC: Carbon steel

Dished end: 4500 dia x 43 thk

Shell : 4500 dia x 36 thk

 

As per code, dished end is to be PWHT. Shell is exempted.

 

My query is whether PWHT is necessary for circumferential joint of dished end to shell (43 thk dished end welded to 36 thk shell)?

 

My understanding is at the joint itself, thickness is 36 mm which need not to be PWHT as per code, however, taper portion (HAZ) of dished end will be more than 38 thickness and hence may required PWHT.

 

Please guide me.

 

 

Best Regards,

Sunil Agrawal
EDTICB-Mumbai (STEQU)
Ph.: +91 22 6777 7237

 

 

[Ranasaria Shivanand Rajendra]

Background:

We have a LTCS pipe upto 45 mm which are internally coated by FBE ( Tuboscope TK 236 ) and welded by special manufacturer’s techniques ie using Thru Kote Sleeves by Tuboscope, exact details of TK236 & Thru Kote Sleeves re attached.

These Sleeves make sure tht during welding, heat do not burn the internal FBE coating on pipe, it’s a proven technique in use by Maersk Qatar.

 

However As the pipes are above 19 mm , as per B31.3 we are supposed to have a PWHT.

 

When I wrote to Tuboscope regarding this issue there response was as below

“ The max. allowance temperature for TK-236 is 200°C. The same is for the Blue Mastic and max. 100°C for the NBR O-rings.

For the PWHT you need min. 250 - 300°C over a longer time so you will have the problem with the destruction of the coating.”

We have addressed this issue to Client, Client’s response is that Thickness upto 25.4 mm can be waived off, but for higher thickness, EPC contractor has to find a solution.

 

 

Question:

As PWHT is not feasible on internally FBE coated pipe, can Code help us to get a justifiable waiver with some improved welding procedure etc or by any other ways.

[pjo...@technip.com]

The two solutions in this case are as follows:

1) Use welding consumable other than CS, like SS or inconnel. with this
solution, you may avoid the PWHT even for 45 mm thickness.
2) Check with the design aspects. i.e. what is the application, (I suppose
it is for Off-shore applications). If you can manage to change the Design
code where there is a possibility of waiving off the PWHT. Best way is to
check with the supplier of the Coated tubes.

But looking at the conditions, (45 mm thickness) the weldimg without PWHT
may be very dangerous from safety point of view as the weld metal will
become brittle even at Room temperature. So, if your minimum design
temperature is less than 60-deg, it is better to find alternate solution.

Best regards,

Prasad Joshi
e-mail: pjo...@technip.com
Phone: +971-(0)2-611-6643




"Ranasaria
Shivanand
Rajendra" To
<ran...@npcc.ae> <material...@googlegroups.com
Sent by: >
materials-welding cc
@googlegroups.com <RBat...@ticb.com>
Subject
[MW:233] RE: 226] RE: 225] RE: 224]
15/09/07 08:48 AM RE: 213] RE: 206] PWHT for joint of

two differentthk - 43 mm to 36mm

Please respond to
materials-welding
@googlegroups.com

Save a tree...please don't print this e-mail unless you really need to.




(See attached file: Basic Info TK-U.B.I Sleeves3.pdf)(See attached file:
TK-236.pdf)


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[Bathula Raghuram (Mumbai - PIPING)]

Members
please put appropraite subject while posting
also a request to all members to create new email every time you post a new querry or info, don't reply to erlier threads, as Google groups has draw back of saving these new thread under the prvious reply.
Pleas take care in future!

________________________________

[Bathula Raghuram (Mumbai - PIPING)]

What dia meters are involve in this?

It is better to go for an ROV for field joint coating, these were used in RPL Jamnagar way back in year 1997-98, i am sure there will much improvement in this field now

For the underground epoxy coated lines (Sea water intake), filed joint coating was done with the help of a robotic head ( i don't remeber the vendor who has done it might be from UK), even smaller dia like 4"-6" line filed welds were coated using this. The head has an inbulit multi purpose attachement ( at three different locations) which can do various operations simulatenously, blasting and cleaning the weld spatter/slag, paint application, and drying. these are monitored remotely thro optic fibre cables and LCD,s.

I am sure it should be availeble in Gulf too.

For PWHT probably the improved heating element like this will give you less damage to the coated area.

www.pih.co.uk/uploads/files/induction_heat.pdf

<http://www.pih.co.uk/uploads/files/induction_heat.pdf>

[Raghuram Bathula]

http://materials-welding.blogspot.com/2007_09_15_archive.html
you may check the above link for more details on How to avoid PWHT and
related consequences

On Sep 15, 11:54 am, "Bathula Raghuram \(Mumbai - PIPING\)"

> winmail.dat
> 9KDownload

[gopal sankar]

This case the only solution is to use ASS weld to avoid post weld heat treatment.You can use E309 electrode provided the no.of joints are very minimal to have cost effective. Temper bead weld techniques cannot be applied in this case due to high thickness.Temper bead weld techniques is suited for repair application only.

 

regards,

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[Sankepalli R.S.Reddy]

At Aramco, we are doing internal FBE coating [APCS 102] of welded joints after  welding, NDT and PWHT [If applicable]. For this our coating contractor is using

1. Crawler arrangement when there is no access to weld surface manually [Example Dia 20" and less]. In this method we have to plan welding sequence of joints by taking into consideration of contractor capabilities i.e., location of weld joint from open end [Our contractor is able to access the weld location situated about 12m from open end]. Still in this method we have to use flange joints at certain locations to access the inside surface.

2. By having manway access in big diameter pipes at regular intervals helps the contractor to do internal coating manually.

WE have to take additional precautions related to pipe supports attached with the pipe by welding. These supports should be located nearer to open ends to enable the contractor to repair damaged FBE coating due to coating burning by welding. The other area that we have to take care is cutting of pipes by gas cutting and edge preparation for welding. Care should be taken not to damage the coating during this operation and if any coating damage is noticed, should be repaired before going to the next stage. 

 

 

 Regards

SRSreddy

PID, Aramco, KSA