Pressure Relief Valve at Heat Exchanger

[daniwibowo]

Dear Honorable Member,

We have Shell and tube heat exchanger named E-201-11. This E-201-11 is exchanger just before pass heater of furnace of CDU. The service fluid is desalted crude (shell) and vacuum residue (tube) from bottom column.
Shell operating pressure is 19.7 kg/cm2 and tube operating pressere is 25.8 kg/cm2.
Pressure desain shell 30 kg/cm2 and pressure desain tube 36 kg/cm2.
Hydrotest pressure shell 43.5 and tube 37.5 kg/cm2.

What the main consideration of installing TSV at outlet of desalted crude?

Now, we are installing spare exchanger for E-201-11 but the type is plate and frame HE.
The operation mode will be one HE operated and one HE spare/stadby.

My question is : Do we need to install relief valve at desalted crude outlet of new HE?

Regards
DW

[fructora]

Plate and Frame Type Exchangers
Relief protection of plate and frame exchangers shall comply with ISO 23251 (API STD 521): “Pressure-Relieving and Depressuring Systems” requirements related to shell and tube heat exchangers. However, an effective hole size is required to determine flow through a *****ed plate.
An effective hole size shall assume a ***** 1.5mm wide along the length of the high or low pressure header.
Fire should not be considered in the design of overpressure protection systems for plate and frame exchangers with elastomeric gasketing that would burn away upon fire exposure.
Plate and frame heat exchangers are more likely to leak through a gasket than through a plate. However, internal plate failures have occurred, generally due to some form of corrosion, such as pitting, *****ing, or general corrosion

[fructora]

A Working Guide to Norman P. Lieberman...
Heat Exchanger Safety Reliefs
Process heat exchangers are ASME coded pressure vessels with a MAWP (Maximum Allowable Working Pressure), just like any other
vessel, for both the shell and tube sides. However, they normally are not protected from overpressuring by a relief valve. The small relief
valves you may see located on the shell and channel head (tube side) are for thermal relief, not for excessive pressure due to accidentally
exposing the exchanger to excessive upstream pump discharge pressure (perhaps because a pump impeller was oversized). Such exchangers
are legally protected from excessive pressure by their flange rating, and not by relief valves.
If you did not wish to provide the extra mechanical strength (i.e.,the extra MAWP), then relief valves are required for heat exchangers.
The same logic also applies for process piping. For instance, 150-psig piping has an MAWP of about 225 psig, depending on its temperature.