Steam Piping

It depends upon the installation. To rate it correctly, the pipe must be rated according to the maximum steam pressure and temperature that the installation could ever experience.

Dear Sir,

I didnt understand the explanation, My doubt is which line will come the outer most in a loop.

By...

For clarification it is not so much the highest or lowest pressure as it is the HIGHEST TEMPERATURE (greatest thermal expansion) vs. the lowest temperature (lesser thermal expansion).

Both, this answer and the one based on pressure will result in the same answer but, it is the expansion that is the critical issue.

The temperature for HP steam is always > MP steam, which is again always > LP steam in the case of saturated steam. This is how it is related. Please refer steam tables for saturated water and steam to get clear idea and for exact values for your pressures correlating to HP, MP and LP steam. By the logic of thermal expansion already explained earlier, HP steam shall have maximum expansion, MP steam will have medium expansion and LP steam will have lowest expansion only because they have the temperature difference as explained above. So to cater to the maximum expansion, HP line should come in the outermost portion of the pipe loop followed by MP line in the middle and LP line in the innermost part of the loop. Again you have to consider the lengths of pipeline before and after loops to actually position all the loops at the same location as that will determine the amount of thermal expansion the loop has to absorb. Hope this helps.

Dear Sir,

Thanks for your explanation,

Regards

Vani