We have experienced leakage from the circumferential weld seam of SHELL at our Plant. Please see attached pictures and WPS showing weld joint configuration. Thickness of shell is about 106 mm and material is A 542 Type B Class 4.

Redoing this weld joint (as per original configuration, by grinding through the base metal completely), entails downtime of several months and high production loss.

Therefore we are looking for other options of repair/leakage containment and seek your recommendations in this regard.

Following option that we are evaluating, is as follows:

1. Grinding/bevelling of weld to a depth of 92 mm, 100 mm along the circumference, placing a strip made from grade P22 pipe and then completing the weld.

I request you to review the above options and let us have your comments. Please also advise if there is any other solution for fixing this leakage, as a short term measure, till the time we have necessary arrangements for complete repairs.

Would appreciate receiving your inputs on urgent basis.

Best regards,

_________________
Syed Osama Nusrat Ali
Exective Engineering (Project)
Fauji Fertilizer Company Limited
Pakistan
email: osama_ali@ffc.com.pk
Cell # +92-3025252018

In situ Leak repairs are routinely carried out in Oil & Gas Industry .I haven't seen that being done in Chemical Plants.You may contact some of the specialist firms in Oil & Gas industry for their opinion.

It appears to be a very serious failure. Please let me know the following:

1. Design code of the shell.
2. Design pressure/ temperature (seems to be designed for high pressure)
3. Results of RT/UTperformed
4. Configuration of weld crack

The material is question is a hardenable steel having bainite structure and usually available in tempered form for pressure vessels to control the hardness of base metal. PWHT is performed to stress relieve the weld joint and to reduce the hardenability of material due to welding operation. Option mentioned in your post cannot be performed w/o PWHT.

ADM

Design code : AD Markblatter
Design pressure/ temperature 158 kg/cm2g / 480 deg.C
Results of RT / UT = Not yet received
Configuration of weld crack = Transverse Crack

Osama

_________________
Syed Osama Nusrat Ali
Exective Engineering (Project)
Fauji Fertilizer Company Limited
Pakistan
email: osama_ali@ffc.com.pk
Cell # +92-3025252018