[MW:12549] RE: 12548] defect on circ-seam of H2 service vessel

// What rectification shall I do on the defective segment on the service point of view?//

 

Shall be repaired by Qualified WPS for which PWHT holding time shall not exceed the 1.2times of PQR holding time.

I hope you might have given 1 hour holding time for the original joint. the second PWHT may be again for 1 hour. So, your WPS shall support for total 2 hours of holding time.

 

Moreover, the simulation heat treatment requirements shall be verified for the applicability.

 

// What are the NDE's required?//

MT/PT on gouged area, reweld, PT/MT on final weld, RT on final weld before PWHT and after PWHT.

 

// Is a local PWHT mandatory at the repaired segment?//

 

Since, PWHT is a service requirement, and shall be carried out after repair, may be locally or complete CS.

 

// Any special precautions for H2 service...//

 

Hardness shall be carried out after PWHT and shall not exceed 22 HRC

 

The important point is design temp -80 deg C. The material selected SA516-60 may not be appropriate for such condition. The UCS curve is supporting up to 80 deg F (Not 80 deg C).

 

If the original vessel is ASME Code stamped, then repair shall be done to NBIC Code with R stamp.

M.Vijayan

 

From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of K.M Hrishikesan
Sent: Tuesday, September 27, 2011 9:14 AM
To: materials-welding
Subject: [MW:12548] defect on circ-seam of H2 service vessel

 

Dear Mr. Pradeep Goswami & other experts...

 

We have a newly fabricated Vessel having following details

 

 

Vessel:  1200 mm ID X 4550 mm TL-TL

MOC: SA 516 Gr 60

Code of constr: ASME section VIII div 1 2007 edn.

Thickness: shell-20mm; DE-24 mm

Design pr- 32.3 kg/sq.cm; Design temp - 80 deg.C

Service: LPG+Naphtha ; Vessel is designed for  Hydrogen service, 100%RT, Fully PWHT; hydrotested ,cleared by TPI, erected at site, yet to be commissioned

 

 

Imperfection (a notch or gouge out)of about 3-4 mm deep and 15 mm long observed on weld seam CS-1 (Top Dished end to shell circ. seam joint ) from inside of vessel. Please see the attached image of segment radiographed by us.

 

My queries...

 

What rectification shall I do on the defective segment on the service point of view?

What are the NDE's required?

Is a local PWHT mandatory at the repaired segment?

Any special precautions for H2 service...

 

appreciate your quick feedbacks..

 

Regards

Hrishi

 

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