Bleeder Trip Valve (BTV)/Non-Return Check Valve in High Temperature Applications

Problem

Valve packing which contains PTFE when installed in Bleeder Trip (BTV)/Non-Return Check valves can be subjected to accelerated corrosion due to the application. Since the check valve stem only rotates and does not rise thru the valve packing it creates a confined space, which is not refreshed via typical valve stroking (rising thru the packing). Problem occurs at high temperatures (>400 deg F).

Solution

Style 7300 packing is a braided flexible graphite packing which contains no PTFE. The configuration would be a 4 ring set with 2 rings of standard 7300 in the center with a 7300HD on either end. 7300HD is a high density 7300 ring used for containment. Between all rings would be a graphite washer. A packing stress of 3000-4000 psi dependent on operating pressure is recommended. If space allows, a hardened carbon bushing installed on the top & bottom of the set is recommended.

An alternative would be to use our nuclear grade pure graphite products (no PTFE) of 524 braided end rings and 6300J die formed graphite. We have seen issues with graphite buildup on ¼ turn type valves which do not have the wiping action of a rising stem valve, which is why the preferred recommendation is Style 7300.

Refer to WEIR Valve Technical Bulletin #11.0.

Product Info

AP STYLE 7300/7300HD