UL 262-2023-07
STANDARD FOR SAFETY Gate Valves for Fire-Protection Service

Standard No.

UL 262-2023-07

Release Date

2023

Published By

Underwriters Laboratories (UL)  US  /  UL

Introduction

UL 262 Standard Overview and Revision Background

UL 262, known as the "Standard for Safety of Gate Valves for Fire Protection," is one of the most important certification standards for fire protection valves in North America. The first edition of this standard was published in 1931 and has undergone eight major revisions. The latest edition is the eighth, released on February 26, 2004, and a major revision was made on July 19, 2023.

The July 2023 revision primarily clarifies the requirements for year of manufacture marking, detailing the requirements for year of manufacture marking in Section 29.1 of the standard. This revision reflects UL's emphasis on product traceability and ensures reliable performance of fire protection valves throughout their lifecycle.

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Scope of Application and Referenced Standards

UL 262 applies to gate valves used in fire protection water piping systems, including externally threaded yoke-type gate valves and non-rising-stem gate valves. These valves must be designed and manufactured to comply with the installation and use requirements of the following NFPA standards:

NFPA Standard Number	Standard Name	Application Area
NFPA 11	Low Expansion Foam Systems	Foam Fire Extinguishing Systems
NFPA 13	Sprinkler System Installation	Automatic Sprinkler Systems
NFPA 14	Standpipe and Hose System Installation	Indoor Hydrant Systems
NFPA 15	Water Spray Fixed Systems	Special Hazard Protection Systems
NFPA 16	Deluge Foam-Water Sprinkler Systems	Combination Foam-Water Systems
NFPA 20	Centrifugal Fire Pump Installation	Fire Pump Systems
NFPA 22	Private Fire Water Tanks	Fire Water Tank Systems
NFPA 24	Private Fire Main Installation	Fire Piping Systems

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Valve Structural Design Requirements

Sizes and Pressure Ratings

According to Sections 5-6 of the standard, externally threaded yoke-type gate valves are suitable for standard pipe sizes 1/2 inch and larger, while non-rising stem gate valves are suitable for standard pipe sizes 2-1/2 inches and larger. The valve pressure rating requirements are:

• 12-inch and smaller sizes: minimum 175 psig (1206 kPa)
• 14-inch and larger sizes: minimum 150 psig (1034 kPa)

Body and Bonnet Materials

The valve body and bonnet must be constructed of a material at least equivalent in strength, rigidity, and corrosion resistance to cast iron or bronze. Castings should be smooth and free of defects such as scale, lumps, cracks, bubbles, and pinholes. Castings must not be plugged or filled, but porosity may be eliminated by impregnation.

Technical requirements for key components

Component name	Material requirements	Special provisions
Gate	Cast iron or equivalent corrosion-resistant material	The center part of the gate over 1 inch should be concave
Stem	Bronze or 300 series stainless steel	Must pass comparative corrosion test
Sealing surface	Bronze or organic coating material	Coating must pass multiple durability tests
Handwheel	Any material that meets the size requirements	Must be marked with the "OPEN" direction and arrow.

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Details of Performance Test Requirements

Corrosion Performance Tests

The standard requires several corrosion tests to ensure the durability of valves in harsh environments:

10-day wet ammonia air stress cracking test: For brass parts containing more than 15% zinc, after exposure to a wet ammonia air environment at 93°F (34°C) for 10 days, there shall be no evidence of cracking under a 25x magnification glass.

Valve stem comparative corrosion test: Other valve stem materials shall not show more general corrosion, pitting, or cracking than bronze materials after exposure to a humid carbon dioxide-sulfur dioxide air mixture and salt spray environment for 30, 60, and 90 days.

Sealing Performance Test

Elastomeric Sealing Material Fixing Test: The valve is subjected to a water flow velocity of 15 ft/s (4.6 m/s) for one hour in the half-open state. The elastic material should not separate, tear, or permanently deform.

Elastomeric Sealing Cycling Test: The valve must continue to meet the leakage test requirements after 1,000 cycles of full opening and closing.

Leakage Test

Different types of valves have different leakage test requirements:

Valve Type	Test Pressure	Allowable Leakage
Metal to Metal Seal	2 Times Rated Pressure	≤1 Fluid Ounces/Hour/Inch Valve Diameter
Elastic Seal	1.5 Times Rated Pressure	Zero Leakage

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Manufacturing and Inspection Requirements

Clause 28 of the standard requires manufacturers to establish necessary production control, inspection and testing procedures, including at least:

1. Factory test for body leakage: When the valve is in the open position, a hydrostatic pressure of twice the rated working pressure is applied to all internal components for at least 15 seconds. The valve body shall not leak or permanently deform.
2. Seat leakage test: Test with a hydrostatic pressure of 1.5 times the rated working pressure or a pneumatic pressure of the rated working pressure.

For metal-to-metal seats, the leakage rate shall not exceed 1 fluid ounce (29.6 ml) per hour per inch of nominal valve size during the hydrostatic test; the leakage rate shall not exceed 0.1 cubic feet (2.83 dm³) of air per hour per inch of nominal valve size during the pneumatic test.

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Marking and Identification Requirements

Per Section 29.1, revised July 2023, each gate valve must be legibly marked with the following information:

• Manufacturer’s or private labeler’s name or identifying symbol
• Valve nominal size
• Distinctive model number, catalog name, or equivalent
• Pressure rating
• Year of manufacture (year marking for a specific time range is permitted)

Marking may be by raised cast letters, etched or stamped metal nameplate, or other equally permanent method. For valves 4 inches and smaller, cast letters must be at least 1/8 inch (3.18 mm) high; for valves larger than 4 inches, letters must be at least 1/2 inch (12.7 mm) high.

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Recommendations and technical points for the implementation of the standard

Recommendations for material selection

When selecting valve materials, priority should be given to proven corrosion-resistant materials:

1. Valve body and bonnet: ASTM A126 Grade B cast iron or equivalent is recommended
2. Valve stem: Bronze (C83600 or C84400) or 300 series stainless steel
3. Sealing surface: Bronze or material that has passed the organic coating test
4. Elastomeric sealing material: Silicone rubber or synthetic rubber that meets UL 157 standards

Test verification strategy

To ensure that the product complies with UL 262 requirements, the following testing strategy is recommended:

1. Establish a complete material certification file, including material test reports for all key components
2. Perform regular production sampling tests to ensure consistency in mass production
3. Establish a corrosion testing laboratory or cooperate with a certified laboratory to regularly verify the corrosion resistance of materials
4. Implement a strict leak testing procedure to ensure that every valve leaving the factory is 100% tested

Marking and traceability system

According to the requirements of the 2023 revision, it is recommended to:

1. Establish a comprehensive manufacturing year marking system to ensure compliance with the requirements of Article 29.1(e)
2. Use a permanent marking method to ensure that the marking is clear and readable throughout the service life of the valve
3. Implement a product traceability system that can trace the specific production batch and material source through the marking information

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Technological Evolution and Future Outlook

Since its first publication in 1931, the UL 262 standard has undergone significant technological evolution:

1. Material technology advancement: from traditional cast iron and bronze to modern stainless steel and special alloys
2. Improved Test Methods: Corrosion testing methods are more scientific and rigorous, with the introduction of multiple environmental simulation tests.
3. Innovative Sealing Technology
4. Intelligent Development: Digital identification and IoT tracking technologies may be introduced in the future.

With the advancement of fire protection technology and the emergence of new materials, the UL 262 standard is expected to continue to be updated to adapt to new technical challenges and safety requirements. Manufacturers should closely monitor standard developments and promptly adjust product designs and production processes.

By fully understanding and strictly implementing the requirements of the UL 262 standard, valve manufacturers can not only ensure their products pass UL certification but, more importantly, provide reliable and durable critical equipment for fire protection systems, providing strong protection for life and property safety.