Oklahoma Department of Labor ITT/ASCO V710 Gas Shut-Off Valves with Proof of Closure Seals
On November 17, 1999, the Oklahoma Department of Labor issued a memorandum reporting an incident at a Frederick, Oklahoma hospital involving a V710 gas shut-off valve manufactured by ITT General Controls in 1977. The memorandum reports that a portion of the nitrite seating surface, which had separated from the disc, became lodged between the seat and disc resulting in leakage and a minor explosion.
Automatic Switch Company (ASCO) acquired certain assets of the General Controls Division from ITT in 1996. All of the valves which we have inspected in the Oklahoma City area are at least 15 years old, were manufactured well before ASCO’s acquisition and thus are the legal responsibility of ITT Fluid Technology. However, ASCO is working closely with ITT and the Oklahoma Department of Labor to determine if there is a problem with these valves.
While our investigation is ongoing, our preliminary findings, based on examination of the valve removed, other equipment installed in the same gas line and discussions with Oklahoma Department of Labor personnel are that the reported problem may be the result of inadequate inspection and maintenance as required by the manufacturer and certain applicable industry
codes and standards. We are also investigating the possibility that the reported ‘”deterioration” of the nitrite seal may be the result of a contaminant present in the gas lines.
Taking advantage of advancements in material technology and manufacturing methods, in 1995 ITT General Controls (prior to ASCO’s acquisition) changed the proof of closure seal from a Teflon impregnated nitrite to 100% Teflon, making the valve less susceptible to chemical attack and better able to withstand adverse conditions that may be encountered in the field. ASCO and ITT are currently conducting tests on the seals to determine if the valve deterioration in the Oklahoma valves was related to unusually high contaminants in the natural gas supply. We want to assure you of our confidence in the V710 valve design which has provided safe, reliable gas control in thousands of applications worldwide for many years.
ASCO’s Installation and Maintenance manuals instruct that the owner/installer must establish a routine inspection schedule to include periodic internal and external leakage checks for all valves of this type. In addition, the valves are to be operated periodically in accordance with manufacturer’s instructions and/or applicable industry codes and standards. We strongly encourage you to remind your customers of this important safety precaution.
We appreciate the concerns that have been raised by the issuance of the field notification by the Oklahoma Department of Labor. At this time, however, there is no evidence to indicate that the problem reported is other than a localized one involving several valves in excess of I5 years old, and whose maintenance history is, at best, questionable.
An important aspect of our continuing investigation is the examination of valves from other areas of the country. Comparison of this seal with those from valves removed from service in other areas of the country may assist us in determining whether the problem arises from contaminated gas.
Therefore, ASCO and ITT would very much appreciate having the opportunity to examine any V710 valves which have been recently removed from service or which you anticipate replacing in the next few weeks. Please contact ASCO General Controls by phone at (800)-423-2387 or by fax at (800) 962-2130 for shipping instructions if you can help.
ASCO is committed to providing the highest quality products for the combustion industry and to working with all of our customers to insure the continued safe, reliable performance of our products.
Very truly yours,
AUTOMATIC SWITCH COMPANY
Valve Service Department
Equipment Product Advisory
December 20, 1999