Exterior gas cock vs. ball valve

[mdr]

Hi all,
Running PE line for an exterior fire pit. I'd like to put a shut-off valve on the line as it exits the meter to allow me to isolate it from the existing under-house gas system. There are many valve choices and I'm trying to understand the differences between them.

When I started this project, I just assumed I would use a full port lever handled ball valve, similar to what I've used on my water supply. They are often specified as 600 wog. I understand that the wog designation is for liquids and that there are other standards for natural gas. So I'm trying to find an appropriate valve for an exterior application.

Grainger carries these apollo gas cocks, - is this what I'm looking for? The Apollo valve catalog assumes the user has a good understanding of what valve to use when/where.

(Also - are these ball valves? If not, why aren't ball valves used?)

Thanks,
Murray

 

[hj]

They are "plug valves", but ball valves are often used.

 

[Sponsor]

 

[Jadnashua]

WOG = water, oil, gas...it will work on gas.

 

[mdr]

Thanks Mr. Jad of Nashua. (pretty area, btw - I did some work for Nashua Corp - started in the winter brrrr for a CA person but got to continue experience the spring and early summer.)

Yes, I understand that WOG = water oil and gas. As an engineer, you might also appreciate this tidbit from Nibco. The WOG standard doesn't really specify suitability for the flow material, but really only pressure rating.

The pressure/temperature rating on a valve or in the literature does not mean that the valve will function satisfactorily within those limits. The pressure/temperature rating SWP and WOG only refers to the pressure-containing vessel – the body and bonnet. The material, wall thickness and design will contain the media up to the rated pressures and temperatures. The rating does not relate to the performance of the trim or the compatibility of the valve to the media. The following are a few descriptions of pressure rating:

 UA’s INSTRUCTION MANUAL FOR STEAMFITTER-PIPEFITTER JOURNEYMEN & APPRENTICES, 1996: “The WOG (Cold Water, Oil, Gas) rating indicates the maximum non-shock pressure at ambient temperatures at which the valve may be used.”

 Stockholm’s Catalog 83 refers to “pressure-containing parts” on the pressure/temperature charts.

 Plant Engineering, “VALVE FUNDAMENTALS”, August 7, 1980: The pressure rating is determined by the design and the allowable stresses for materials of construction at the temperature limit The WOG rating indicates the maximum non- shock pressure at which the valve may be used.

 Chemical Engineering, “A GUIDE TO SELECTING MANUAL VALVES”, September 1, 1986: “Maximum pressure ratings are based on body wall and flange design.”

 MIL-V-18436E, “VALVES, CHECK, BRONZE, CAST IRON & STEEL BODY” March 2, 1981, Section 3.6.2, WOG Rating: “The WOG rating is the maximum non-shock pressure, expressed in psi, for which the pressure-containing parts of the valve are​

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rated when the coincident media temperature is between -20°F and 150°F for bronze body and cast-iron body valves and -10°F and 100°F for steel body valves. The WOG rating indicates the ability of the valve to withstand the pressure effect of water, oils, and gases and does not imply that a WOG-rated valve will necessarily withstand the potentially deleterious effect of all aqueous solutions, petroleum products and gaseous media unless appropriate material selectivity has been exercised.”

The WOG rating has not been a good description and there is movement within the industry to the more descriptive CWP (Cold Working Pressure). Regardless of what it is called, it remains a limitation of the pressure valve only. The valve type, material and trim are different for each application. The pressure/temperature limitations of the pressure- containing vessel are a few of the several variables that must be considered.
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[Jadnashua]

The ball in many ball valves is SS, the sealant gasket is PTFE, and the body bronze or brass. NG pressure is minuscule compared to most things like water supplies. My ball valve for my gas grill is now about 15-years old...works just fine. It gets cycled every time I use my grill as I don't like the idea of the flexible, removable hose and the internal valves on the grill to be what stops flow.

Yeah, it can get cold here in the winter, and hot in the summer, but the changes are partly what makes it interesting! That, and the no sales tax or personal income taxes...it's usually wet enough so widespread forest fires are not a factor and, while they do occur, earthquakes are generally small and more frequent than most people realize. We do see an occasional tornado, but nowhere near what tornado alley does nor do they have the ferocity.