UTS OF REINFORCEMENT PAD

[212197]

WE HAVE A VESSEL. SHELL QUALITY IS SA333 GR 6. NOZZLE IS SA333 GR6. REINFOREMENT PAD IS SA516 GR 70.
UTS AT ROOM TEMPERATURE (ACTUAL) - 471 MPA AGAINST REQUIRED 486 MPA.
YS AT ROOM TEMPERATURE (ACTUAL) - 306 MPA AGAINST REQUIRED 260 MPA.

REINFORECEMENT PAD CALCULATION AS PER ASME UG-37 DOES NOT INVOLVE UTS.
MY CLIENT WANTS JUSTIFICATION FOR ACCEPTANCE OF THE DEVIATION IN UTS.

WHAT BASIS COULD WE PROVIDE ? WE CAN NOT REJECT THE MATERIAL.

 

[TGS4]

Two things:

1) please turn of the caps lock - it's considered yelling here

2) the reinforcing pad is an integral party of the pressure boundary, and as such the materials must meet the Code requirements, including the material minimum strength requirements. Your material does not. There I would reject it.

(The allowable stress used in the calculation assumes a minimum UTS. So, even though there is no UTS in the calculation, it is relevant nevertheless.)

 

[david339933]

REINFORECEMENT PAD CALCULATION AS PER ASME UG-37 DOES NOT INVOLVE UTS.

No, but it uses correction factors fr3 and fr4 which are the ratios of Sp/Sv. Since Sp for SA-516-70 is based on UTS, what would you use for the allowable stress?
Also, you should read UG-93(a)(1).

 

[SnTMan]

212197, you need to reject the non-conforming material. You are on very shaky ground. You may wind up with a vessel you cannot ship.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[Christine74]

Is the material SA-516 Gr. 65/SA-516 Gr. 70 dual-certified ? If so, you might still be able to meet the area replacement requirements with the existing repad.

Most SA-516 plate material these days is triple or quadruple-certified to cover grades 55/60/65/70.


-Christine

 

[SnTMan]

Agreed, if it meets a permitted specification, it may be used.

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[212197]

Christine74 (Mechanical) - it is not dual certified.

Actually I did not get your point. If I require SA 516 Gr 70 which is having more UTS requirements than that of Gr.65.
How it will help if there would have been the certificate which means Gr.65/Gr.70..& plate meets requirement of Gr. 65 ?

Pl. guide.

https://www.eng-tips.com/

 

[david339933]

Again, read UG-93(a)(1).....it tells you that you MUST have an MTR for plate material. If not, then an option would be to qualify the material per UG-10. You would have to do chemical analysis, mechanical tests, and possibly heat treatment. Think I would get a new repad.

There are bigger problems here than a missing MTR....you need to re-evaluate your quality program. Traceability of material is important.

 

[Christine74]

212197, my point was that reinforcing pads are generally somewhat overdesigned using commercially available plate thicknesses, so it's possible that you could rerun the nozzle reinforcement calculation using a lower strength SA-516-65 repad material and it might work.

If you still don't meet area replacement requirements with the SA-516-65 repad, you might also be able to use larger fillet welds for the pad-to-shell and/or the nozzle-to-pad welds.


-Christine

 

[212197]

Guys I am sorry. Today I got feedback from my QC DEPARTMNET that UTS was 501 before carrying out simulated heat treatment (stress relieving) but it is lowered to 471 Mpa against required 486 Mpa.Soaking time was 150 minutes & soaking temperature was 630 degree cel. This reinforcement pad will undergo stress reliving in job for 75 minutes. We carried out simulated heat treatment for 150 minutes considering one probable repair after stress reliving in actual job.