1. Forged Socket-Weld Pipe Fittings Product Introduction

   Product Overview

   Forged socket-weld pipe fittings are manufactured in accordance with GB/T14383‑2021 and ASME B16.11 standards, formed through an integral die-forging process and finished by precision machining. The product range mainly includes socket-weld elbows, tees, crosses, couplings, reducing joints, caps, branch outlets, and unions. The connection type is socket welding, where the steel pipe is inserted into the socket bore of the fitting and welded with an external fillet weld, offering easy assembly and high structural strength. These fittings are primarily used in small-bore medium-to-high-pressure industrial piping systems ranging from DN6 to DN100, widely replacing threaded fittings to address the leakage issues associated with threaded connections under high-pressure conditions.

   Product Materials

   • Carbon Steel: A105, A350 LF2, suitable for steam, oil products, and general oil and gas media under high-temperature and low-temperature conditions;
   • Stainless Steel: A182‑F304, F304L, F316, F316L, suitable for corrosive media, pure water, and chemical process pipelines;
   • Alloy Steel: A182‑F11, F22, F91, used for high-temperature and high-pressure steam piping in power plants.

   Pressure Ratings

   Available in three pressure ratings — 3000#, 6000#, and 9000# — matching SCH80, SCH160, and XXS wall-thickness steel pipes respectively. The pressure rating of the fittings must not be lower than that of the matching steel pipe to ensure the safety of the overall piping system.

   Product Features

   1. Integral forged forming: Dense structure with excellent high-pressure and impact resistance, suitable for conditions with significant pressure fluctuations;
   2. Socket-weld connection structure: Simple installation, no bevel preparation required, high on-site construction efficiency;
   3. Complete range of specifications: Covers full-size and reducing elbows, tees, couplings, branch outlets, etc., meeting various piping requirements such as flow splitting, direction changes, size reductions, and equipment connections;
   4. Stable performance: High-temperature resistance, resistance to certain media corrosion, and superior sealing reliability compared to threaded fittings;
   5. Strict quality control: Magnetic particle (MT) and penetrant (PT) non-destructive testing available; each product is stamped with material, standard, pressure rating, and heat number for full traceability.

   Application Fields

   Widely used in small-bore high-pressure pipelines in industries such as petroleum refining, coal chemical, thermal power plants, hydrogen refueling stations, air separation units, marine and offshore engineering, high-pressure gas fire suppression, hydraulic systems, and pharmaceutical equipment. Commonly applied in instrument impulse lines, sampling lines, equipment connections, and internal process piping of skid-mounted equipment.

   Usage Instructions

   1. The most commonly used pipe sizes are DN15‑DN50; DN100 is the upper limit for socket-weld fittings. For large-diameter pipelines, butt-weld fittings are recommended;
   2. Welding is limited to the external fillet weld only; no welding is performed inside the fitting;
   3. Select the appropriate material based on media temperature and corrosiveness; use low-temperature carbon steel for cryogenic conditions and 316L stainless steel for highly corrosive environments;
   4. Not suitable for special conditions involving severe erosion or intense alternating impact loads.

Forged Socket-Weld Fittings (Socket-Weld Pipe Fittings) Technical Specifications

Execution Standards: ASME B16.11‑2021 (American Standard), GB/T 14383‑2021 (Chinese National Standard), including elbows, tees, couplings, crosses, caps, branch outlets, and unions; Process: die forging + machining, suitable for DN6‑DN100 (1/8"‑4") small-bore high-pressure pipelines.

1. Pressure Ratings & Matching Pipe Wall Thickness

Table

Note: The pressure rating of socket-weld fittings must match the wall thickness of the mating steel pipe; the fitting rating must not be lower than the pipe rating.

2. Common Material Grades

Carbon Steel

• A105/A105N (high-temperature carbon steel, petrochemical, steam, oil products)
• A350 LF2/LF3 (low-temperature carbon steel, cryogenic media)

Stainless Steel

• A182‑F304/F304L, F316/F316L (corrosive media)
• F321, F347 (high-temperature creep resistance)

Alloy Steel

• A182‑F11/F12/F22/F91/F92 (high-temperature high-pressure steam, boiler piping)

3. Main Dimensional Parameters (General)

1. Connection Type: Socket welding (SW), pipe inserted into socket bore, external fillet weld; socket bore provides welding clearance.
2. Socket Bore Depth J: DN15‑DN40 minimum depth 9.5‑12.5mm; DN50 and above minimum 16mm.
3. Nominal Size Range: DN6～DN100 (NPS 1/8"～4"), with DN15‑DN50 being the most commonly used in engineering.
4. Angle Specifications: 90° elbows, 45° elbows; full-size/reducing tees and crosses; full couplings and half couplings.
5. Surface Finish: Carbon steel: blackening / rust-preventive oil; Stainless steel: pickling and passivation.

4. Service Conditions

1. Media: steam, oil products, natural gas, nitrogen, hydrogen, water, and certain corrosive chemical media.
2. Temperature Range:
   • A105 carbon steel: ‑29 to 425℃
   • 304/316 stainless steel: ‑196 to 538℃
   • Alloy steel: suitable for high-temperature steam above 550℃.
3. Applicable Systems: High-pressure small-bore piping; not for large-diameter pipelines; not suitable for severe alternating loads or heavy erosion conditions.

5. Inspection and Marking

1. Non-destructive testing: magnetic particle (MT), penetrant (PT); ultrasonic testing (UT) available for high-pressure conditions.
2. Marking: stamped with standard, material, pressure rating, specification, and heat number.

6. Product Selection Guidelines

1. For high media temperatures, select A105/F22 alloy steel; for corrosive media, select 316L; for low-temperature service, select LF2.
2. For SCH80 pipe, select 3000# fittings; for SCH160 pipe, select 6000# fittings.
3. Socket-weld connections are limited to external fillet welding only; no welding is performed inside the fitting.