Is the Straight Stainless Steel Bulkhead Fitting with Male NPT for Metric Pipe, M774LM compatible with metric tubing of different wall thicknesses and pressure ratings?

Straight Stainless Steel Bulkhead Fitting with Male NPT for Metric Pipe, M774LM is compatible with metric tubing of different wall thicknesses and pressure ratings, subject to the tubing’s outer diameter and wall thickness determining the allowable working pressure. Because the fitting is LET-LOK® style and made from AISI 316 stainless steel, it provides a robust, leak-tight connection across a range of metric tube sizes when the correct tube OD and wall thickness are used. Compatibility considerations: - Tube OD and wall thickness: Use the tube dimensions specified for the fitting. The fitting’s sealing and gripping performance—and therefore the maximum safe pressure—depend on matching the tube OD and minimum wall thickness the fitting is designed to accept. - Pressure rating: The allowable working pressure is a function of the tube’s material, OD and wall thickness; confirm the combined rating of the fitting and the chosen tube meets your application's pressure requirements. - Application conditions: For aggressive chemicals, extreme temperatures or critical services (e.g., nuclear, high-pressure process lines), verify compatibility of tube material and wall thickness with operating conditions and applicable standards. Recommendation: Consult the manufacturer’s dimensional and pressure tables for M774LM or provide the exact tube OD, wall thickness and operating pressure/temperature so the correct tube/fitting combination can be confirmed.

Can the Straight Stainless Steel Bulkhead Fitting with Male NPT for Metric Pipe, M774LM be used with tubing made from different materials (e.g., copper, Hastelloy) and how does material choice affect sealing and compatibility?

Yes — the Straight Stainless Steel Bulkhead Fitting with Male NPT for Metric Pipe, M774LM can be used with tubing made from different materials (e.g., copper, Hastelloy), but compatibility and sealing depend on material properties and joint preparation. Key considerations: - Hardness and deformation: AISI 316 fitting is relatively hard and corrosion-resistant; softer tubing (copper) can deform under ferrule or compression fitting loads, potentially requiring reduced torque, backing ferrules designed for softer metals, or a sleeve to prevent damage. Harder alloys (Hastelloy) hold threads and ferrule grip well but may need higher torque. - Galvanic corrosion: Dissimilar metal contact (316 SS with copper or certain nickel alloys) can create galvanic couples in conductive fluids or wet environments. Use insulating sleeves, coatings, or compatible materials if corrosion risk is critical. - Chemical compatibility and temperature: AISI 316 is broadly compatible, but verify both tubing and fitting against process media, temperature, and pressure. Hastelloy may offer superior resistance for highly corrosive media; copper may be unsuitable for some chemicals. - Sealing behavior: LET-LOK® sealing performance relies on proper ferrule engagement and tube surface finish. Smooth, unscratched tubing and correct wall thickness are required for leak-tight seals. Softer tubes may need careful torque control to avoid extrusion; harder or thin-walled tubes may require support sleeves. - Pressure rating: Allowable working pressure is governed by tubing OD and wall thickness, not just fitting material. Ensure tubing material strength and wall thickness meet system pressure requirements. - Installation and maintenance: Use correct installation procedure, proper torque, and inspect for compatibility (corrosion, galling). For mixed-metal joints, consider anti-seize or appropriate surface treatments where needed. Conclusion: M774LM can work with copper, Hastelloy, and other tube materials if you verify galvanic risks, chemical compatibility, tube hardness/wall thickness, and follow LET-LOK® installation practices to ensure reliable sealing and longevity.

Straight Stainless Steel Bulkhead Fitting with Male NPT for Metric Pipe, M774LM

All products, LET-LOK precision connectors/

Additional information

Material	SS – stainless steel

The straight bulkhead fitting type LET-LOK® with external NPT thread is a high-performance connector designed for secure and reliable installation of metric tubing in demanding industrial environments. Manufactured from premium AISI 316 stainless steel, it ensures exceptional resistance to corrosion, aggressive chemicals, and extreme operating conditions, making it an ideal choice for applications in the chemical, petrochemical, pharmaceutical, energy, nuclear, and process engineering sectors. Its robust construction guarantees long-lasting durability, while the precision-engineered design provides leak-tight connections that enhance system safety and efficiency. The allowable working pressure depends on the tubing’s outer diameter and wall thickness, enabling flexible adaptation to specific project requirements. Engineered to meet the highest industry standards, this fitting supports optimal flow performance, reduces maintenance needs, and contributes to the overall reliability of complex installations. With its proven LET-LOK® technology, it offers a trusted solution for professionals seeking uncompromising quality and operational security in critical processes.

List of product variants

Article number	Product variant name	Nominal inner diameter	Working pressure [bar]
HM-LM774LM-06-02-SS	Bulkhead fitting for 6 mm tube, GZ 1/8" NPT, SS	-	-
HM-LM774LM-06-04-SS	Bulkhead fitting for 6 mm tube, GZ 1/4" NPT, SS	-	-
HM-LM774LM-08-04-SS	Bulkhead fitting for 8 mm tube, GZ 1/4" NPT, SS	-	-
HM-LM774LM-10-04-SS	Bulkhead fitting for 10 mm tube, GZ 1/4" NPT, SS	-	-
HM-LM774LM-12-04-SS	Bulkhead fitting for 12 mm tube, GZ 1/4" NPT, SS	-	-
HM-LM774LM-12-06-SS	Bulkhead fitting for 12 mm tube, GZ 3/8" NPT, SS	-	-
HM-LM774LM-12-08-SS	Bulkhead fitting for 12 mm tube, GZ 1/2" NPT, SS	-	-

The straight bulkhead fitting type LET-LOK® with external NPT thread is a high-performance connector designed for secure and reliable installation of metric tubing in demanding industrial environments. Manufactured from premium AISI 316 stainless steel, it ensures exceptional resistance to corrosion, aggressive chemicals, and extreme operating conditions, making it an ideal choice for applications in the chemical, petrochemical, pharmaceutical, energy, nuclear, and process engineering sectors. Its robust construction guarantees long-lasting durability, while the precision-engineered design provides leak-tight connections that enhance system safety and efficiency. The allowable working pressure depends on the tubing’s outer diameter and wall thickness, enabling flexible adaptation to specific project requirements. Engineered to meet the highest industry standards, this fitting supports optimal flow performance, reduces maintenance needs, and contributes to the overall reliability of complex installations. With its proven LET-LOK® technology, it offers a trusted solution for professionals seeking uncompromising quality and operational security in critical processes.