MSS SP-70 is an industry standard developed by the Manufacturers Standardization Society (MSS) of the United States, which specifically regulates the design, manufacturing and testing requirements of flange-end and threaded gray cast iron gate valves.
Applicable scenarios and restrictions
- Application areas
Mainly used in medium and low pressure pipeline systems (such as nominal pressure ≤1.6MPa), typical scenarios include drinking water, water supply and drainage, sewage treatment, fire protection pipe network and irrigation system;
Applicable to non-corrosive media, gray cast iron material limits its use in acidic or high temperature and high pressure environments.
- Pressure and temperature rating
Pressure rating : Follow Class 125 (approximately corresponding to PN16), adapted to conventional municipal engineering needs; Temperature range : Gray cast iron valve body is usually limited to room temperature to below 120°C (specifically affected by sealing materials)
Structural design features
Connection method
Flange connection: Comply with ANSI B16.1 flange standard, bolt hole spacing and sealing surface type (such as raised face RF) must match the pipeline;
Threaded connection: Suitable for small-diameter pipelines (usually ≤DN50) to reduce leakage risk.
- Valve body and opening and closing structure
Valve body material: Gray cast iron (ASTM A48 standard), ensuring a balance between cost and strength; Valve stem type: Mainly dark stem (non-rising type) design, compact structure and suitable for space-constrained scenarios.
Sealing form
Soft sealing type: The gate is coated with EPDM or NBR rubber, and low-pressure sealing is achieved through elastic deformation; Metal sealing type: Copper alloy valve seat and cast iron gate are matched, which has better durability but lower sealing accuracy.
Manufacturing and Testing Specifications
Design compliance: The valve body structure length complies with the ASME B16.10 standard, and the flange size must match the ASME B16.1; Performance test: Shell strength test and sealing test (such as water pressure test 1.5 times the nominal pressure) are carried out according to the requirements of MSS SP-70; International compatibility: Parallel with German DIN, British BS and other standards, supporting global supply chain adaptation.
- Typical product examples
Class 125 cast iron gate valve: flange end connection, non-rising stem structure, DN65 caliber, suitable for fire protection pipe network; Z41T/Z45T series: copper core valve seat design, taking into account wear resistance and economy, widely used in municipal water supply systems.
Selection recommendations
Corrosive media: Avoid using gray cast iron materials, and give priority to stainless steel or fluorine-lined valves;
High-pressure scenarios: Switch to cast steel gate valves (such as API 600 standard products); Installation space: Concealing stem gate valves are more suitable for well chambers or narrow areas.