Top Questions

Safety and safety-relief valves should be installed vertically with the drain holes open or piped to a convenient location. All piping must be fully supported.

Installing a safety valve in any position other than with the spindle vertical and upright may adversely affect performance and lifetime and may not meet code. Installation in any position other than vertical can violate code standards.

Maintenance should be performed on a regular basis. An initial inspection interval of no longer than 12 months is recommended. The user must establish an appropriate inspection interval depending on the service conditions, the condition of the valve and the level of performance desired.

The ASME Boiler and Pressure Vessel Code does not require nor address testing installed valves. The only thing the codes states are design and installation requirements, such as some valves must have a lifting lever.

For instance, for Section VIII: “Each pressure relief valve on air, water over 140F, or steam service shall have a substantial lifting device which when activated will release the seating force on the disk when the pressure relief valve is subjected to a pressure of at least 75% of the set pressure of the valve”.

It is normal for spring-operated safety valves to exhibit leakage or simmer/warn, as the operating pressure approaches the nameplate set pressure, typically in the 80%-90% range of nameplate set pressure. The ASME Boiler and Pressure Vessel Code does not require a specific seat tightness requirement. A certain level of leakage is allowed per manufacturers’ published literature. Kingston defines seat tightness standards as follows: Factory Standard Seat Tightness Performance: o Hard Seat Valves – no audible leakage at 20% below nameplate set.

Soft Seat Valves – no audible leakage at 10% below nameplate set. At very low set pressures (20 psi and below), the ratio of the downward spring force as compared to the upward pressure force is very small. In these cases, it may be impossible to achieve seat tightness. Use soft seat valves for superior seat tightness in applications which fall within the soft seat material temperature limitations. Although soft seat valves will typically provide a higher degree of seat tightness than metal seats, Factory Standard does not ensure bubble-tight seats, regardless of seat material.

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Typically, the valve should be nameplate set to open at the MAWP (Maximum Allowable Working Pressure) of the vessel the valve is intended to protect. There is a tolerance to actual set pressure, which means a valve set at 100 psig nameplate may open slightly above or below 100 psig. Consult the current ASME Boiler and Pressure Vessel Code for tolerance classes and special situations when the set pressure may be different than the MAWP.

The orifice diameter is the internal opening of the valve and is used to calculate the flow capacity of the valve. Metric or English makes no difference. It’s the inside hole. The inlet size is the interface or the size/type of the threads where you attach the valve. As of publication Kingston Valves do not come in metric sizes, only NPT (National Pipe Thread).

General Questions

No. Gage pressure (psig) is used to set valves so the effects of weather and altitude on set pressure can be ignored.

A soft seat safety relief valve typically uses an elastomer material, such as Silicone, FKM (Viton™), EPDM (Teflon™), Nitrile (Buna-N) or PTFE as the sealing material in the internals of the valve depending on the compatibility of media flowing through the valve.

Use soft seat valves for superior seat tightness in applications which fall within the soft seat material temperature limitations. Although soft seat valves will typically provide a higher degree of seat tightness than metal seats, Factory Standard does not ensure bubble-tight seats, regardless of seat material.

A hard seat safety relief valve is a metal-to-metal seated valve, which usually uses a metal disc or ball as the internal sealing surface against the orifice or internal passageway in a safety relief valve.

A hard seat safety relief valve is excellent in corrosive or extremely high temperature applications.

A safety relief valve is designed to open and relieve excess pressure from pressure vessels, boilers, or other industrial equipment and to reclose and prevent the further release of media (air, gas, steam or liquids) after normal conditions have been restored. 

ASME B16.34 Valves Flanged, Threaded and Welding End applies to new construction. It covers pressure-temperature ratings, dimensions, tolerances, materials, nondestructive examination requirements, testing, and marking for cast, forged, and fabricated flanged, threaded, and welding end and wafer or flangeless valves of steel, nickel-base alloys, and other alloys Wafer or flangeless valves, bolted or through-bolt types, that are installed between flanges or against a flange are treated as flanged-end valves. Alternative rules for NPS 2½ and smaller valves are provided.

Intended for manufacturers, owners, employers, users and others concerned with the specification, buying, maintenance, training and safe use of valves with pressure equipment, plus all potential governing entities.
Careful application of these B16 standards will help users to comply with applicable regulations within their jurisdictions, while achieving the operational, cost and safety benefits to be gained from the many industry best-practices detailed within these volumes.

This standard is to be used in conjunction with equipment described in other volumes of the ASME B16 Series of Standards as well as with other ASME standards, such as the Boiler and Pressure Vessel Code and the B31 Piping Codes.

The National Board of Boiler and Pressure Vessel Inspectors is the third party that certifies our manufacturing/quality program. They also test and certify flow on each code valve periodically.

The NB Certificate and Samples of the CoC are available in the Quality section of the Downloads area. Downloads Page The National Board “Redbook” or the Published List of Certified Valve Manufacturers also contains this information. We are listed as the F.C. Kingston Company (KNG).

All the valves are listed there in Section B, Page 40 of 88. http://www.nationalboard.org/SiteDocuments/NB18/PDFs/NB18ToC.pdf

Kingston Check Valves designed for lubricated compressor applications will not perform in non-lubricated systems. Internal parts on these valves require lubrication provided to the compressor. If installed on an oil-free compressor these valves will wear prematurely and possibly cause damage to the compressor.

The Model 205, for example, has an internal piston to dampen the hammering effects of some compressors. The piston and sleeve are precision engineered to fit snugly and require oil to keep from overheating and wearing quickly or seizing.

Yes. Liquid Applications: Liquids tend to be incompressible, meaning they cannot be compressed like air. Liquids can be under pressure but as soon as the volume changes they immediately lose all pressure (pressure goes to zero). There are three accepted definition in the industry for liquid applications. They are: start to leak, first steady stream and full flow. For Liquid applications – Kingston defines “Set Pressure” as the first steady stream of flow out of the valve.

Back pressure reduces set pressure on a one-to-one basis, i.e., a valve set at 100 psig subjected to a backpressure at the outlet of 10 psig will not actuate until system pressure reaches 110 psig. Back pressure drastically reduces capacity; typically, backpressure of 10% of set pressure will decrease capacity by 50%.

Specific capacity reduction should be determined by the user on a case-by-case basis by flow testing. Back pressure in excess of 10% of set pressure is not recommended.

Section VIII UG-136(a)(3) states, “Each pressure relief valve on air, water over 140 degree, or steam Service shall have a substantial lifting device which when activated will release the seating force on the disk when the pressure relief valve is subjected to a pressure of at least 75% of the set pressure of the valve.

Code Case 2203 states the lifting device may be omitted provided: The user has a documented procedure and an associated implementation program for the periodic removal of the pressure relief valves for inspection and testing, and repair as necessary.

The omission is specified by the user. The user shall obtain permission to omit the lifting device from the authority having jurisdiction over the installation of pressure vessels.

ASME stands for American Society of Mechanical Engineers. ASME is a not-for-profit membership organization that enables collaboration, knowledge sharing, career enrichment, and skills development across all engineering disciplines, toward a goal of helping the global engineering community develop solutions to benefit lives and livelihoods. Founded in 1880 by a small group of leading industrialists, ASME has grown through the decades to include more than 100,000 members in 140+ countries. Thirty-two thousand of these members are students.

The National Board of Boiler and Pressure Vessel Inspectors was created in 1919 to promote greater safety to life and property through uniformity in the construction, installation, repair, maintenance, and inspection of pressure equipment. The National Board membership oversees adherence to laws, rules, and regulations relating to boilers and pressure vessels.

It may not be. Warn/simmer or seat leakage is sometimes mistaken for set pressure. Visible or audible leakage or system pressure drop is not set pressure. The correct definition of set pressure is: For liquid service, first vertical steady stream. For liquid service, first vertical steady stream.

For some valves in air/gas service (Models 230, 330, 330S, 333S, C776), First audible. Variance of set pressure is allowed, i.e., a Section VIII air valve with a nameplate of 100 psig set pressure may open from 97 psig to 103 psig but will be factory set around 102 psig.

Maintain a minimum operating gap of 10% between the system operating pressure and the safety valve’s nameplate set pressure. Since direct spring-operated safety valves may “Simmer” or “Warn” at 90% of the nameplate set pressure, and since the factory standard leak test performed at 80% of nameplate set pressure, better seat tightness performance can be expected with an operating gap of 20%.

This drain hole is required on some models by the ASME Boiler and Pressure Vessel Code. It is intended to prevent any condensate from accumulating in the body that may freeze or corrode internal valve parts and prevent the valve from opening.

The drain hole should be piped away to safely dispose of any discharge or condensate.

At this time Kingston Valves have not been certified with the “The National Association of Corrosion Engineers” (NACE International).

The Canadian Registration Number (CRN) for a boiler or pressure vessel is the tracking number used by the Canadian Provinces to track Canadian certified valve designs.  The letter C following the designation is for a design registered in all Canadian jurisdictions.

Here at Kingston, we employ skilled and innovative engineers who specialize in custom valve design. If you have a design dilemma and would like a custom valve for your design needs, please contact our Help Desk so we may better assist you. You can reach our offices Monday through Friday from 6:30am to 5:00pm at (800) 997-0500.

See chart on the back of our line card or in our brochures.

  • Size (inlet & outlet)
  • Media (Air, Liquid, Gas, etc.)
  • Flow requirements (scfm for air/gas, gpm for liquids, lbs/hr for steam service)
  • Required Set Pressure
  • Temperature considerations
  • Materials of Construction considerations

ASME Section VIII is the section of the ASME Boiler & Pressure Vessel Code (BPVC) that covers pressure vessels. It specifically refers to the pressure vessels that operate at pressures, either internal or external, that exceed 15 psig. ASME Section I covers steam applications on fired vessels (boilers).

The lowest operating temperature varies between valves due to seat material. The lowest temperature that can be applied is -250°F.

Company FAQ

Frederick Charles Kingston founded the F.C. Kingston Company in the City of Los Angeles in 1908. In 1909, the first Kingston Safety Valve was born.

Here at Kingston, we manufacture several valves including Safety Valves, Check Valves, Control Vales, Solenoid Valves, Air Compressor Valves, and even Custom Valves.

Kingston Valves is currently located in Torrance, California. You can visit us at 23201 Normandie Ave., Torrance, CA 90501.

Visit our LinkedIn page or the Storm Industries Career page here for current job postings.

Yes, SMG provides internship opportunities for enrolled college students for fall, spring, and summer seasons. Please contact our HR department [email protected] for available openings.