Pound Rating

The word 'pound' has many meanings in many different contexts.

Could you give us a clue as to which field of endeavour you are applying the term.

A pound of sugar is different to a 'pound per square inch' is different to a 'foot pound' of torque.

Dear Sir,

Question is related to Mechanical engineering.

Pound rating used in piping industry for presuure temp rating and for flange selection.

Hi Soheb,

I have often wondered about this too, as when you look at the temp/pressure rating tables, the values listed bear no obvious relationship to the rating on the flange.

I really hope someone can clear this up for both of us!

If you're referring to pipe line flange ratings, it refers to the maximum working pressure. For example if you were designing a compressed air pipeline to operate at 100 psig, you would probably select 150 lb flanges, fittings, etc. This might be an over simplification for some, but, you get the idea and can go from here. Check with the manufacturer for ratings at elevated temperatures, etc.

Thanks very much for your info

I was working on an answer, than decided to first read the existing ones.

I saw yours and there was no more a need for mine...

(I have expressed this in giving you an additional "Good Answer"...)

Wangito.

My dears wangito and Soheb

Thank you very much and you are welcome.

Gowelding is a Very interesting site, includes vessels, heads, thickness of pipes, ASME B16.5 flanges, ASME suggested forms, welding, design stresses, European codes EN288, WPS, PQR, WPQ, P-Number, preheating, welding symbols, weld failure ... etc...etc ... etc.

thanks abdel, this is really informative..regards- rodel

Thank you gabriel.rodel, you are welcome.

Same as using "S" to identify the stainless steel pipe schedules like 5S, 10S, 40S and son on. Cheers, Ash Bandy

The desription "pound" is actually a misnomer - the correct description is "class 150" or "class 300". The class of a flange refers to the temperature/pressure ratings that the flange can safely handle - each flange class has a chart that gives the allowable pressures at various temperature, the chart can be obtained from suppliers. To state that a 150 class flange can handle 100 pounds of pressure can be dangerous without referring the specific temperature/pressure chart.

From http://www.weldbend.com/Technical%20Data/Pressure%20Temperature%20Ratings%20For%20Flanges/prestemprateforflng.htm

These figures agree with those calculated from Abdel's link.

I'm glad you asked the question because at the beginning of my career someone told me what it meant and I've carried that incorrect answer along with me since then without really thinking about. You can tell I don't have to do mechanical design. Here is a link that will provide some history.

http://www.ebaa.com/pdf/pdf/FL-01.pdf

It is simple to define that 100 Pounds equal to 7 Kg/Cm2. SO 150 pounds nearly equal to 10 Kg/Cm2 & 300 Pounds Equal to 21 Kg/Cm2

I hope u would have understood about his answer.

Rajakumar