PRV for thermal expansion

[PAN]

The fuel oil line (pipe size 6&quot has steam tracing and insulation. The fluid temperature is greater than effect from direct sunlight. Do we need to install PRV for this application? Please comment.

 

[dcasto]

Because you have source on this line, it should have a PRV sized for the maximum heat that can be transfered to line from the steam tracing if the line is blocked from other PRV's on the system. Your correct in thinking that thermal input would be nil as compared to the steam heat.

Here is a solution I've seen on lines that can be blocked in and have some small thermal expansion that would cause an over-pressure. At the valve that can be closed, install a small (3/8&quot line around the valve. The small line will have a check valve in it such that if the line's pressure increases above the line on the other side of the shut valve, it will open and allow a small amount of liquid to pass into the other line and then to a PSV on that side of the shut valve. Of course, small valves can be placed on each side of the check valve to allow inspection of the check valve. This is a great way to remove all the thermal valves on meters, lines that have lots of headers and valves, ect... You can even limit the amount or rate that flows through the valve by adding a restrictive point in the tubing, these are commonally available by tubing fitting companies that normally size the restrictions to slowly bleed air on tubing vent lines.

 

[stanier]

Another solution is to drill a small hole in the check valve flap if this doesnt compromise your operations