Difference Between MSS SP-114 and MSS SP-112 Standards

In the (PVF) pipe, valve, and fitting industry, standards are more than just paperwork, they are needed for safety, compatibility, and long-term performance.

Whether you are in engineering, procurement, or quality control, understanding the right standards helps make sure that piping components meet demands and requirements.

Two widely recognized standards are MSS SP-114 and MSS SP-112. While both come from the Manufacturers Standardization Society (MSS), they serve different purposes. SP-114 specifies corrosion-resistant threaded and socket-weld pipe fittings, while SP-112 sets the quality benchmarks for cast surface finishes.

This blog will explain each standard, highlight their differences, and help you decide which is more relevant for your needs. Stainless Steel MSS SP-114 Fittings

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What is MSS SP?

MSS stands for the Manufacturers Standardization Society of the Valve and Fittings Industry, a non-profit founded in 1924. MSS develops standards, known as Standard Practices (SPs), to guide the design, materials, dimensions, and testing of valves, pipe fittings, pipe flanges, and related equipment.

These standards are voluntary but widely adopted in industries such as oil and gas, chemical processing, food and beverage, and water treatment. They often work alongside ASME and ASTM specifications to ensure products are safe, compatible, and high performing.

MSS SP-114: Product Specification for Pipe Fittings

The standard practice title of MSS SP-114 is Corrosion Resistant Pipe Fittings Threaded and Socket Welding, Class 150 and Class 1000. The 2018 edition of MSS SP-114 outlines requirements for corrosion-resistant cast or forged fittings, typically in stainless steel grades such as Type 304 or Type 316.

Key points for Class 150 fittings:

Pressure rating: Up to 300 psi at 150°F, decreasing at higher temperatures.
Materials: Austenitic stainless steels per ASTM A351 or ASTM A182.
Design: Heavy-pattern construction with thicker walls for better corrosion resistance.
Threading: Per ASME B1.20.1 standards.
Applications: Common in chemical plants, food processing, marine systems, and other environments where corrosion is a concern.

SP-114 ensures fittings meet strict dimensional, marking, and performance requirements, making them dependable for long-term service.

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MSS SP-112: Quality Standard for Surface Finishes

The standard practice title of MSS SP-112 is Quality Standard for Evaluation of Cast Surface Finishes - Visual and Tactile Method. The 2021 edition of MSS SP-112 provides a visual and tactile inspection method to rate the surface finish quality of “as cast” parts, including valves, pipe flanges, and pipe fittings.

Key points:

Uses a 10-surface, 3D comparator tool to assess roughness (scale of 1 = smooth to 10 = rough).
Focuses on detecting casting defects e.g. surface finish inclusions and rough surfaces.
Applies after cleaning the cast surface, before coating or machining.
Does not define product specs, it is purely a quality control standard.

SP-112 is often used alongside other MSS, ASME, or ASTM standards to ensure the casting quality meets requirements.

Key Differences Between MSS SP-114 and MSS SP-112

Aspect	MSS SP-114	MSS SP-112
Primary Focus	Product specifications for Class 150/1000 corrosion-resistant fittings	Surface quality evaluation for cast components
Scope	Materials, pressure ratings, dimensions, markings for pipe fittings	Surface roughness grading
Direct Pressure Relevance	Defines Class 150 ratings	Indirect, better surfaces improve long term pressure by reducing corrosion risk
Materials	Corrosion Resistant alloys such as Stainless Steel Type 304 & Type 316	Cast materials: no direct material specifications but ensures finish quality
Applications	Ready to install fittings	Inspection of casting quality
Compliance Role	Standalone manufacturing standard	Supplementary quality standard

How The SP-114 vs. SP-112 Standards Work Together

If you are purchasing or specifying fittings, MSS SP-114 tells you exactly what the product must be. If you are inspecting cast pipe fittings, MSS SP-112 ensures they meet acceptable surface quality.

To demonstrate their quality commitment, many manufacturers will produce pipe fittings to SP-114 specifications and use SP-112 to ensure that the product(s) meet surface requirements.

Inventory Considerations

Stock MSS SP-114 fittings if you are serving end-users who need corrosion-resistant, ready to install products.
Use MSS SP-112 if you manufacture or inspect cast components and need consistent quality verification.
Best practice: Stock MSS SP-114 fittings and confirm they meet SP-112 surface standards for maximum reliability.

Advantages and Disadvantages of Each Standard

SP-114 Advantages:

Proven corrosion and pressure resistance.
Heavy-pattern design for durability.
Standardized dimensions for interchangeability.

SP-114 Limitations:

Higher cost due to material and build quality.
Limited to threaded/socket-weld types.

SP-112 Advantages:

Simple, non-destructive inspection.
Improves product reliability by catching defects early.

SP-112 Limitations:

Subjective, relies on trained inspector judgment.
Adds inspection time and tooling cost.

Conclusion

While MSS SP-114 and MSS SP-112 both support quality and performance in piping systems, they serve different roles. SP-114 ensures the fitting meets product specifications, while SP-112 confirms the casting’s surface quality.

For most wholesale distributors and end-users, SP-114 will be the primary standard, but pairing it with SP-112 inspections offers the highest confidence in performance.

Ready to talk MSS SP-114 and MSS SP-112 compliant components? Contact Merit Brass for piping solutions that meet today’s toughest industrial standards and how we can help you meet your distribution goals.

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Author: Addison Towne, Marketing Intern