Structural Carbon Steel vs Carbon Steel For Pressure Purposes 3

[IJR]

Friends

If mechanical properties(yield strength, ultimate strength, elongation and CVN) as well as carbon contents(and carbon equivalent) of these two steels can be shown to equal or approximately equal, is it legal to interchangeably use them?

Any other important criterion?.

respects
ijr

 

[arunmrao]

How about impurities,structural defects, microstructure details are they comparable?

 

[SnTMan]

Does your code of construction permit it?

 

[IJR]

arunmrao

That is what I am trying to find out: what else is the criterion that divides the line between the two steels

SnTMan
Steels in structural codes are listed down. And steels for pressure applicationas are listed too. The problem is sometimes you can not find what the codes want and engineering knowledge helps the judgment.

respects
ijr

 

[SnTMan]

IJR, listed where?

The codes of construction don't "want" anything. They typically permit various materials to be used, subject to certain rules.

Regards,

Mike

 

[IJR]

SnTMan

You are making me tired. But that is fine, let me put this question:

Can I use a structural grade for a pipe that will be used in pressure application if thickness calculations and some basic mechanical properties agree to those listed in ASME for pressure applications?

There could be a parameter I have to watch out for.

What could it be?

respects
ijr

 

[SnTMan]

IJR, referring to ASME Sec VIII, Div 1:

You can, for example, use SA-36 plate for pressure boundary parts, such as cylinders and heads. The allowable stresses at various temperatures are tabulated in ASME Sec II, Part D, the SA-36 material specification is found in Sec II, Part A. It is permitted. It is, however, subject to the limitations in Sec VIII, Div 1, Part UCS, UCS-6(b).

This does not tell you that it is suitable for a particular service.

You may only use a material for, again as an example, Sec VIII, Div 1 construction if is is listed in Sec II, Part D AND is listed as permitted for Sec VIII, Div. 1. Not all materials listed are permitted.

Now if you are talking about non-listed materials, in general, no, you may not use them for ASME construction, even though they appear to be "equivalent" to listed materials.

It might help get you an answer if you would be more specific about code of construction, if any, and the particluar materisla in question.

Regards,

Mike

 

[metengr]

Can I use a structural grade for a pipe that will be used in pressure application if thickness calculations and some basic mechanical properties agree to those listed in ASME for pressure applications?

Simple answer; not enough information to answer your question.

What is the SPECIFIC application for the above? In other words, is this material going to be used to fabricate a component for a piping system, pressure vessel, pickle jar, tea kettle ......

 

[stanier]

The elements and physical properties mentioned may be the same but the manufacturing process may vary as may other small elements. In addition to this materials for pressure work may require additional certification and testing to structural grade materials.

That said if you can get agreement with your customer & perhaps their insurer then you can make a case for anything. I can recall carbin steel tubing used for the manufacture of car exhausts being used for a small gas line in the desert.

 

[IJR]

metengr

Often we have low pressure pipes(10-30bar) specified for water and similar non-chemicals. Pressure pipes are often not available in stock, and it is quite easy to find a similar pipe of structural grade with the same CVN and carbon content. How about using the structural grade then, I mean why not A36 instead of say A

But as stanier pointed out, certification is one of the problem. But in my area, certification can often be bypassed by a technical letter approved by a third party elected by the client. Unfortunately I have to do all the work while the third party waits.

I apologize for not asking clearly enough

respects
ijr