Maximum Design Pressure of A106 and A53 3

[PAN]

Refer to a paper from council of engineers in my country, the limitation from code for pressure piping define as follows –

ASTM A106 : 2500 psi
ASTM A53 : 600 psi

I cannot find above limitation in ASME B31.3. Moreover, they also have the same allowable stress at room temperature. The calculated pressure for both materials should be the same.

I also check the pressure rating of flange class 1500 (mat. group 1.1), the maximum pressure is higher than 250 barg. If I use pipe A106-B and refer to my council, the allowable working pressure will be less than flange rating.

I do not want to conclude that the interpretation of my council is incorrect. However, in my work experience, I never use pipe A106-B at the pressure over 2500 psi. Can anyone guide me about the source of above limitation (from any code for pressure piping)? Please advise me.

 

[StressGuy]

I think that's the first time I've ever seen anything like this - a blanket statement of a maximum pressure for a material regardless of pipe size and wall thickness. Quite frankly, it doesn't make a lot of sense to me.

What is this paper you refer to? Quite honestly, the only thing I can come up with that makes any sense in my mind is a general concern regarding the amount of stored energy the piping system would hold, especially for a vapor/steam service. I could see the nuke people coming up with a limitation like this.

btw - be careful about that wall thickness calculation. If your A53 isn't seamless, then you've got the Ej quality factor. So, your calculated thickness for A53 may not be the same as for A106.

Edward L. Klein
Pipe Stress Engineer
Houston, Texas

"All the world is a Spring"

All opinions expressed here are my own and not my company's.

 

[stanier]

This limitation doesnt exist in any international code that I am aware of whether it is AS 4041, BS 806, ISO, JIS.

It doesnt make a lot of sensne to impose such a limitation when there are factors/levels applied to design, fabrication and NDE to cater for pressure and risk.

It may be that a company standard has been used for this basis, The particular standard may include pipe, fittings and valves, The valves maybe cast iron bodied and that imposes the upper limit of design pressure. Somehow it may have beeen carried over to a standard. Who knows?

 

[PEHasan]

Please refer to Table 2-1.1 of ANSI B16.5 for Pipe Flanges and Flanged Fittings.

 

[PAN]

Thanks to confirm my understanding. The paper is a revealed examination paper for mechanical engineers (Boiler/Pressure Vessel/Piping) of COE in Thailand. I will try to ask for clarification with the council later.

 

[PZas]

I am not familiar with the document in question. However, I do know of one similar situation where there is no dependency on wall thickness for the allowable internal pressure.

Think way back to the solid casing cannons used in naval ships of the 1800's and early 1900's. The US military found that for a given cannon size increasing the wall thickness beyond a certain point results in no increase and sometimes a decrease in the strength of the material. This is why modern naval rifles are layered in their design.

There may be a referency some other place in the paper that specifies a minimum size or assumes one and it is possible that beyond this size you have a maximum pressure threashold. However I have never seen anything like this in person.