stamping marks by low die stress stamp on inner surface of pressure parts

[lgracio]

Is it allowed stamping marks by low die stress stamp on inner surface of pressure parts?
For instance on plates that are going to be used on manufacturing of end plugs will be installed on both top ends of header pipes. For some reasons of fabrication process, the supplier is asking to make stamp marks on inner surface in direct contact with steam and pressure.

LPSG-Engineering Solutions
Mechanical Engineer
Portugal-Setubal

 

[metengr]

Check with your AI. I would not allow it.

 

[AFG03082015]

I wouldn't be comfortable with doing it, the stamps will act as stress risers whether they are of the low stress die type or not

Increasing stress concentrations is going to have a negative effect on fatigue life.

But as metengr says, your AI is the only person who could deem it acceptable or not if he is the one to sign it off

 

[r6155]

In a short time, inner stamp will dissapear due corrosion.

Regards
r6155

 

[marty007]

As a fabricator, we have been forced to complete ASME PART stamping on surfaces exposed to fluids on a couple of occasions.

For example, we fabricated a replacement u-tube bundle with welded tube-tubesheet joints for an in-service heat exchanger where the tubesheet was too thin to complete the stamping on the outside edge. The tubesheet also was not extended to include the bolting pattern, so we couldn't stamp on the face between bolt holes. Our only choices for stamping were on the shellside or tubeside faces of the tubesheet in the small areas not taken up by tubes.

We confirmed acceptance of this with our customer before proceeding, but in some cases your are put in a position of no other acceptable options...

 

[lgracio]

Hi everybody, many thanks for your clarifications and sharing your experiences.

It is also my opinion that any stamp marking over inner surface will create an increasing of stress concentrations and is going to have a negative effect on fatigue life.

We had some situations with Heat-Exchangers on tubesheets, some stamp marks are on surface in contact with steam/water, and still visible during operation due to zone less affected by corrosion.

Anybody knows if there is any code case or interpretation on ASME code or other Code regarding this subject?

Thanks.
Best year 2017 for all!

LPSG-Engineering Solutions
Mechanical Engineer
Portugal-Setubal

 

[shamino]

There is nothing that prohbits it by Code, at least in Asme 8 Div 1. You don't need to ask the AI either, if he says you can't do it then ask him where in the code it states it. Your QC manual may address it, but probably not.

Welders routinely will stamp their welder ID next to their welds on the inside of vessels. Stress risers are negligible.

 

[r6155]

shamino, there are restrictions to use stamps. Please see:

UW-37 (f) ...........be available to the Inspector;
or a stamp may be used provided the vessel
part is not deformed and the following additional requirements
are met:
(-a) for ferrous materials:
(-1) the materials shall be limited to P No. 1 Gr.
Nos. 1 and 2;
(-2) the minimum nominal plate thickness shall
be 3/16 in. (5 mm), or the minimum nominal pipe wall
thickness shall be 0.154 in. (3.91 mm);
(-3) the minimum design metal temperature
shall be no colder than −20°F (−29°C);


ASME SA-20 13.2.2 Except as allowed by 13.4, the required markings for
plates 1⁄4 in. [6 mm] and under in thickness shall be by paint
marking or by steel die stamping using low-stress (either
round-nose or interrupted-dot) impressions

UG-77 (b) Where the service conditions prohibit die-stamping
for material identification, and when so specified by the
user, the materials manufacturer shall mark the required
data on the plates in a manner which will allow positive
identification upon delivery.

Regards
r6155