SS6935 304L stainless steel elbow

304L Stainless Steel Elbow Description

304L stainless steel elbows are manufactured from an austenitic alloy with a low carbon content to prevent sensitisation during welding. The carbon content of ≤0,03 % prevents the precipitation of chromium carbide in the heat-affected zones, thereby maintaining the corrosion resistance in welded assemblies. The solution annealing at 1 050 °C followed by rapid water quenching produces an optimal grain structure, while pickled surfaces (Ra ≤0,8 µm) facilitate passivation. With 18–20% chromium, which develops an auto-repairing oxide layer, these pipe elbows are resistant to pitting corrosion in chloride-containing environments. Their mechanical properties include a tensile strength of ≥485 MPa and an elongation of 40%, thereby accommodating thermal loads from low temperatures (–200 °C) to high temperatures (425 °C). Electropolished options achieve Ra ≤0,4 µm to prevent biofilm formation in sanitary applications.

304L Stainless Steel Elbow Applications

• Chemical Processing: Corrosive liquid transfer lines, reactor discharge systems
• Pharmaceutical Industry: USP Class VI-compliant distributors for bioprocessing
• Marine: Seawater cooling circuits, pipelines for desalination plants
• Food/Beverages: CIP/SIP system networks, aseptic filling lines
• Semiconductor: Ultra-pure gas distribution systems

304L Stainless Steel Elbow Packaging

Our products are packed in customised cartons of various sizes, selected according to the material dimensions. Small items are securely placed in PP cartons, while larger items are positioned in bespoke wooden crates. We ensure strict packaging customisation and utilise appropriate cushioning materials to provide optimal protection during transit.

Packaging: Carton, wooden crate, or customised.

Please refer to the Packaging Details for further information.

Manufacturing Process

Testing Procedures

(1) Chemical composition analysis – verified using techniques such as GDMS or XRF to ensure compliance with purity requirements.

(2) Mechanical properties testing – includes tensile strength, yield strength and elongation tests to evaluate material performance.

(3) Dimensional inspection – measures thickness, width and length to ensure compliance with specified tolerances.

(4) Surface quality inspection – examines surfaces for defects such as scratches, cracks or inclusions using visual and ultrasonic inspection.

(5) Hardness testing – determines material hardness to confirm uniformity and mechanical reliability.

Further details are available in the SAM Testing Procedures.

Frequently Asked Questions about 304L Stainless Steel Elbows

Q1. Which welding methods are most suitable for joining 304L stainless steel elbows with carbon steel pipes without causing corrosion?

Use GTAW (WIG) or GMAW (MIG) welding with minimal heat input to reduce dilution and carbide precipitation. Select a nickel-based filler metal (e.g. ENiCrFe-3) to close the metallurgical gap between stainless steel and carbon steel. After welding, apply a corrosion-resistant coating (e.g. epoxy) to the heat-affected zone and avoid extended moisture exposure in order to prevent galvanic corrosion.

Q2. How can I restore the surface of a scratched 304L elbow without professional tools?

For minor scratches, use a stainless steel cleaner with a non-abrasive cloth and wipe gently in the direction of the grain. For deeper scratches, apply a passivation gel (e.g. based on citric acid) for 30 minutes, rinse thoroughly and polish with a microfibre cloth. Avoid steel wool or harsh chemicals, as these may damage the passive layer.

Q3. Is 304L suitable for high-temperature steam applications?

304L is oxidation resistant up to a temperature of 870 °C (1 600 °F); however, it may experience carbide precipitation at grain boundaries when exposed for prolonged periods to temperatures between 425 °C and 870 °C (800 °F to 1 600 °F). For repeated steam exposures above 500 °C (930 °F), consider using 316L or stabilised grades such as 321 to prevent intergranular corrosion. At lower temperatures, 304L functions reliably provided that adequate ventilation is available to avoid condensate formation.

Related Information

1. Common Processing Methods

304L billets are hot-forged into seamless pipe sections at 1 150 °C. Elbows are produced by mandrel bending at 900–1 050 °C and then solution annealed at 1 050 °C followed by water quenching to dissolve carbides. Precision trimming ensures right angles within a tolerance of 0.5°. For socket weld ends, internal machining is carried out according to the ASME B16.11 specifications. Pickling after forming using HNO₃/HF removes scale, and passivation in 30% nitric acid restores the chromium oxide layers. For electropolishing (used in sanitary grades), a phosphoric sulphuric electrolyte is employed at 15–30 VDC. Final validation comprises hydrostatic tests at 1.5 times the nominal pressure and PMI using XRF spectroscopy.