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Old 02-11-2008, 05:02   #1
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Thru Hull Valve Rating Question

I am replacing the ball valves in my Tartan 37. I am curious about the rating of these valves. The ones I took out were WOG 600, which seems like ridiculous overkill. As I understand, WOG 600 means that the valve is rated Water Oil and Gas for 600 lbs/sq in. If you think about the weight of the boat (let's exaggerate and say it weighs about 18000 lbs fully loaded) and spread that over 300 sq. ft of hull (this probably understates the hull surface area), you get something like 5 lbs/sq in. of pressure. Am I making a math error? Can somebody help me with this? I have a WOG 400 and a WOG 800 at my local chandlery. How do designers specify these valves?
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Old 02-11-2008, 05:46   #2
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600 psi WOG (“non-shock cold water, oil and gas pressure”), and 150 psi WSP (“working steam pressure”) are standard ratings for brass/bronze ball valve bodies.

I think the 400 WOG may be gate valves (not suitable).

See also:
Instructions for Installation of Thru-Hulls & Valves (Groco):
http://www.cruisersforum.com/gallery...=500&userid=79
http://www.cruisersforum.com/gallery...=500&userid=79
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Old 02-11-2008, 06:21   #3
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The way to calculate the pressure on the valve is to take the distance the valve is underwater in feet and divide by 2.25 (144 sq in/sq ft / 64 lb/cu ft). Thus a valve 2 ft below the surface has less than 1 psi differential pressure. You are right, its not stressing the 600 psi valve.
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Old 02-11-2008, 06:50   #4
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What I meant to say, is that almost any quality Bronze Ball Valve will be rated at least 600 psi WOG.

ABYC Standard H-27, SEACOCKS, THRU-HULL CONNECTIONS, AND DRAIN PLUGS, specifies that:

27.5.2 Seacocks shall be designed and constructed to meet ANSI/UL 1121, Marine Through-Hull Fittings and Sea-Valves.

27.5.3 Thru-hull fittings shall be designed to meet ANSI/UL 1121, Marine Through-Hull Fittings and Sea-Valves.

27.7.1 A seacock shall be securely mounted so that the system will withstand 500 pounds of static force applied for 30 seconds to the inboard end of its connecting fitting, at any point in its most vulnerable direction, without the system failing to perform as intended.
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Old 03-11-2008, 10:51   #5
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Still Have Question

This is not a gate valve. It is a Groco Ball Valve and it appears to be bronze and it is stamped WOG 400. How can I tell if this is compliant with ANSI/UL 1121? I went to the Groco Website and could find nothing there except the WOG designation.
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Old 03-11-2008, 12:24   #6
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Groco type “IBV & IBV-S” Valves are UL Marine Listed.

The “IBS” Ball Valve is 400 WOG rated.
Untitled Document

The “IBV-S” Ball Valve is 1000 WOG rated.
Untitled Document

UL Standard 1121 Marine Through-Hull Fittings and Sea-Valves
Materials: The components of a through-hull fitting or sea valve shall be formed of galvanically compatible materials having the strength and resistance to corrosion necessary to withstand intended and abnormal use to which they are likely to be subjected.
A part made of drawn brass or machined from brass rod containing more than 15 percent zinc shall be subjected to the 10-Day Moist Ammonia-Air Stress Cracking Test (Section 19). After being tested, a brass part containing more than 15 percent zinc shall show no evidence of cracking or delamination when examined using 25X magnification.

Thru-hull fittings that meet ABYC H-27 are entitled to so mark the fitting, and thru-hull fittings that are UL Listed are also entitled to so mark the fitting.

• The Listing Mark of Underwriters Laboratories Inc. on the smallest unit container in which the product is packaged or on the product is the only method provided by UL to identify products manufactured under its Listing and Follow-Up Service.

UL publishes an annual Directory of Marine Products that contains Listings and Classifications and Recognitions in effect as of an annual date. Manufacturers that have submitted thru-hull fittings and sea valves for testing and that have passed UL 1121 standard, are listed in this catalog. The catalog identifies which particular models, and sizes of specific manufacturers that have achieved UL Listing and are entitled to display the UL Listing Mark.
Marine products catalogs in general do not indicate which, if any, of the “Bronze” thru-hull fittings offered for sale are UL Listed or meet H-27, in which case one should query the manufacturer directly.

Groco
Phone: 410-712-4242
Fax: 410-712-0160
Email: info@groco.net
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