3 replies to this topic

[pravin164]

Dear Sirs,

I would deeply appriciate your comments on the following case.

I am deisgning a new shell & tube exchnager in existing system (Inlet Outlet piping). Tube rupture case has been omitted from potential overpressure causes for the system since the H.E is deisgned with 10/13 rule.
Tube side of H.E. is with lower design pressure (equivalent to 10/13 of shell side pressure).Since it is revamping case i dont want to disturb the existing piping system at inlet and outlet of tube side but tube inlet/ outlet piping design pressure is less then the required 10/13th of shell side deign pressure.

Does this system requires PSV for tube rupture still because of piping system design integrity.

Thanks

[fallah]

pravin,

At first it is to be noted that the 10/13 rule is modified to "corrected hydrotest pressure" rule according to API 521 Fifth Edition (section 5.19.2).

Then, without any sketch of the system showing the location of spec break in inlet/outlet piping and tube side integration and HE isolation valves, just a conservative design could be accepted in which the design pressure of the tube side should be considered equal to that of inlet/outlet piping and therefore seems the PSV for tube rupture would be needed in order to keep piping system design integrity.

Fallah

[pravin164]

Sir,

Thanks a lot for your valuable comment.

Upto what extent the inlet/outlet piping system to be deisgned with pressure equal to tube designe pressure. Hence PSV (Tube-rupture)can be avoided.

Pravin..

[fallah]

Upto what extent the inlet/outlet piping system to be deisgned with pressure equal to tube designe pressure. Hence PSV (Tube-rupture)can be avoided.

pravin,

Up to where might be affected by overpressure due to probable tube rupture in HE tube side...

One more point:

Contrary to your especial case, in most cases the design pressure of the lines connecting equipment are higher than that of equipment will result in connecting lines wouldn't have required to be protected by dedicated PSV's and the PSV's on relevant equipment with set pressures lower than the connecting lines will protect both equipment and the lines. Based on this standpoint, the design pressure of the piping around equipment is considered equal to that of equipment up to the first isolation valve in each connection line.

Fallah

Edited by fallah, 25 June 2012 - 06:23 AM.