MSS SP-114 Unions | Class 150 / 1000 Corrosion-Resistant Stainless Steel
SUNHY supplies MSS SP-114 unions for corrosion-resistant, serviceable pipe connections in process and utility lines. Designed for controlled make/break, these unions are widely specified where fast maintenance access, commissioning support, and repeatable sealing are required.
We offer Class 150 and Class 1000 options with NPT threaded and socket weld (SW) ends, focusing on 304 / 316L stainless steel. Each lot can be supported with MTC (EN 10204 3.1), dimensional verification, and optional PMI/NDT per project requirement—ready for site acceptance and documentation handover.
- Serviceable union, easy access
- Compact connection, simple install
- Standard threads, reliable make-up
- Clear traceability, heat ID
- Fits BOM directly, size ready
- Docs available, project spec
Specification & Standard
Nominal Size
Commonly NPS 1/4″ – 4″ (other sizes on request)
Connection
Threaded Union (NPT) / Socket Weld Union (SW)
Seat Type
Conical Joint / Flat Seat (as specified)
Standards
MSS SP-114 (corrosion-resistant union fittings)
Threads: ASME B1.20.1 (NPT) or BSPT on request (per project spec)
Pressure Class
Class 150 / Class 1000 (as specified)
Union Design
Three-piece design for serviceable pipe connection (make/break as required)
Materials
Stainless Steel 304 / 316L common (other grades on request)
Manufacturing
Investment Cast Union / precision machining (casting heat/lot traceability)
MSS SP-114 Unions | Serviceable Stainless Pipe Connection (Class 150 / 1000)
SUNHY supplies MSS SP-114 unions for projects that need a clean, serviceable pipe connection with corrosion-resistant stainless materials. Compared with permanent joints, a union allows controlled make/break during commissioning, flushing, maintenance, and future line changes.
Our range covers Class 150 union MSS SP-114 and Class 1000 union MSS SP-114 selections, with Threaded Union (NPT) and Socket Weld Union (SW) options. Standard material focus is 304 / 316L stainless steel for chemical, water, utility, and general industrial services where corrosion resistance and repeatable assembly matter.
Key Advantages
- Corrosion Resistant Union – stainless material focus supports long-term service in wet/chemical environments.
- Three-piece design – fast disassembly for maintenance without cutting the line (when specified by design).
- Investment Cast Union – precision casting with machining control for consistent seat/fit-up (per lot control).
- Thread/End consistency – thread gauging and dimensional checks help reduce site rework and fit-up risk.
- Project documentation – request MSS SP-114 dimensions, MTC, PMI, and inspection level per spec.
Technical Summary
| ITEM | SPECIFICATION |
|---|---|
| Product | MSS SP-114 Pipe Union (Conical Joint / Flat Seat) |
| Pressure Rating | Class 150 / Class 1000 (as specified) |
| Connection | Threaded Union (NPT) / Socket Weld Union (SW) |
| Material Focus | MSS SP-114 Stainless Union: 304 / 316L common (other grades on request) |
| Manufacturing | Investment Cast Union (precision cast) + machining control; lot traceability available |
| Inspection & Docs | MTC (EN 10204 3.1), dimensional inspection; PMI/NDT/third-party inspection as specified |
Procurement tip: To quote quickly, send your BOM with size, class (150/1000), end type (NPT/SW), seat type (conical/flat), and material (304/316L).
Standard note: MSS SP-114 is commonly specified for corrosion-resistant union fittings in Class 150/1000 ranges. It is different from ASME B16.11, which is typically referenced for higher-pressure forged fittings. Selecting the correct standard helps align dimensions, rating, and acceptance requirements to your project spec.
MSS SP-114 Dimensions | Class 150 Threaded Union (NPT)
Engineers often search MSS SP-114 dimensions to confirm fit-up and take-offs. The table below is the standard layout used in project submittals. If you need the full dimension sheet and MSS SP-114 weight chart, send your size list and rating to receive a matched drawing package.
Table: MSS SP-114 Class 150 Threaded Union Dimensions
| NPS | Class | End Type | A (End-to-End) | B (Nut / Body) | C (Seat / Face) | Weight |
|---|---|---|---|---|---|---|
| 1/4" | 150 | NPT | — | — | — | — |
| 3/8" | 150 | NPT | — | — | — | — |
| 1/2" | 150 | NPT | — | — | — | — |
| 3/4" | 150 | NPT | — | — | — | — |
| 1" | 150 | NPT | — | — | — | — |
Table: MSS SP-114 Weight Chart (Template)
| NPS | Class | Connection | Material | Approx. Weight (kg) |
|---|---|---|---|---|
| 1/2" | 150 | NPT | 304 / 316L | — |
| 1/2" | 1000 | NPT / SW | 304 / 316L | — |
| 1" | 150 | NPT | 304 / 316L | — |
Need confirmed dimensions? Share your project spec and end type (NPT / SW), seat style (conical / flat), and rating (Class 150 / 1000). We will return a dimension sheet aligned to your submittal format.
Product Assembly | How to Install MSS SP-114 Unions
Installation Dimensional Drawing
MSS SP-114 pipe unions are selected to keep piping serviceable. Correct installation depends on seat condition, alignment, and controlled tightening. Final procedures should follow your project spec and be performed by qualified personnel.
Recommended Assembly Steps (Threaded Union - NPT)
- Verify the union – confirm NPS, rating (Class 150/1000), seat type (conical/flat), and material (304/316L) match the BOM.
- Check thread & seat – keep threads clean; inspect sealing faces for dents or transport damage.
- Apply sealant – use approved thread sealant/tape per your spec (avoid contamination on the seat faces).
- Align the line – ensure the two pipe ends are aligned; misalignment is a common cause of leakage.
- Tighten in control – tighten to achieve a stable seal; do not over-torque. Re-check after initial pressure test.
- Leak test – hydrotest/air test per project requirement; record results if needed for site acceptance.
Recommended Assembly Steps (Socket Weld Union - SW)
- Fit-up – confirm socket depth/land; set insertion gap per welding practice and your WPS.
- Tack & align – tack in multiple points to prevent distortion and keep the seat alignment stable.
- Weld per WPS – control heat input; clean and finish as required (especially for stainless).
- Inspection – visual inspection first; PMI/NDT as specified; final pressure test after spool completion.
Project support: We can assist with BOM review, marking/traceability, and documentation pack (MTC / PMI / inspection) to match your receiving checklist.
Related Products
FAQ
What is an MSS SP-114 union used for?
An MSS SP-114 Union is a corrosion-resistant pipe fitting designed for specific industrial applications. Unlike generic iron fittings, it adheres to the MSS Standard Practice for austenitic stainless steel (Grades 304/316), defining strict wall thickness and pressure ratings. It is used primarily in chemical processing, pulp/paper, and steam systems where standard plumbing fittings would fail due to corrosion or pressure.
Class 150 vs Class 1000 MSS SP-114 unions-how do I choose?
The choice depends on your system’s pressure requirements and manufacturing preference:
Class 150 (Investment Cast): Rated for 300 psi at ambient temperature. Best for standard industrial lines requiring precise flow tolerances and cost-efficiency.
Class 1000 (Forged/Barstock): Designed for high-pressure applications. The forging process provides superior structural density and integrity for critical safety environments.
Do you supply threaded (NPT) and socket weld (sw) unions?
Yes, the MSS SP-114 standard explicitly covers both Threaded (NPT) and Socket Weld (SW) configurations. Regardless of the connection type, these unions are manufactured as “Heavy Pattern” fittings, offering a thicker wall and higher corrosion allowance compared to light-pattern ISO 4144 generic fittings.
Why mention investment casting for MSS SP-114 stainless unions?
Investment casting is the standard manufacturing process for Class 150 fittings. This method creates smooth internal flow paths and maintains precise dimensional tolerances that sand casting cannot match. It ensures the fitting meets the 300 psi CWP rating while minimizing turbulence and pressure drop within the piping system.
Can you provide MSS SP-114 dimensions, weight chart, and inspection documents?
Yes. Engineering data is critical for verification. MSS SP-114 unions are roughly 20-30% heavier than generic fittings due to thicker walls. For example, a standard 2-inch Union has an end-to-end length of approximately 2.76” (Socket Weld) or 3.45” (Threaded). We provide full dimensional charts and Mill Test Reports (MTRs) to confirm material compliance.