is it necessary to use the saddle wear material the same as shell material? 1

[gh61]

is it necessary to use the saddle wear material the same as shell material? (pressure vessels designed by asme)
for example in my heat exchnger the shell material is a106-b and i want to use st52-3 for wear plate materials.
thanks

 

[Dhurjati Sen]

Dear gh61,

Depends. If the service is at ambient temperature, then you may get away with a different (I assume a poor quality CS compared to the shell plates) saddle material.

I have seen it in quite a few vessels, but if I'd be the owner, I would not go for such a practice.

Regards.

DHURJATI SEN
Kolkata, India

 

[r6155]

It depends on the design conditions, the wear plate can be avoided.

Regards

 

[weldstan]

Often times wear plate materials are of higher alloy or higher carbon materials than the shell material depending on the service environment. I'm concerned that the OP seems to have so little experience in vessel design and construction. I hope he has someone in his company to guide him.

 

[Christine74]

Saddle wear plates typically aren't made from the same material as the shell to which they attach because there's no need to make them out of pressure vessel quality plate. In this particular case it would silly to use A-106-B material to make the wear pads since this is a piping material specification.

ASME Section VIII Div. 1 only requires the wear pads to be made from a weldable material. Most of our clients just require that the saddle wear pads be of the same nominal material grade as the shell (e.g. 2 1/4 Cr - 1 Mo wear pads for 2 1/4 Cr - 1 Mo shells) in order to avoid welding dissimilar metals.


-Christine

 

[r6155]

Wear plate is applicable if required by calculations.

St 52-3 is equivalent to SA-572 Gr50 (PNumber 1 Group 1), hence you can weld to SA-106 Gr B (P1 G1)

Can you tell us shell diameter?

Regards

 

[weldstan]

I have seen A-36 specified/used for saddle wear plates numerous times.