Is the Straight fitting with GZ BSPT for metric tubing, brass, M768LR compatible with stainless steel or polymer tubing, and are special seals required?

Straight fitting with GZ BSPT for metric tubing, brass, M768LR is designed for metric tubing and is made of brass. It can be used with stainless steel or polymer tubing only if the tubing outer diameter and wall thickness match the couplingâs specified allowable working pressure criteria and if the tube material is mechanically compatible with brass fittings (mechanical strength, temperature range, chemical compatibility). For stainless steel tubing: generally compatible.stainless tubing meets strength and pressure requirements; no special seals are normally required because LET-LOKÂ® style fittings form a metal-to-metal/ferule seal. Ensure tube OD and wall thickness meet the published allowable working pressures and that galvanic corrosion between brass and stainless is acceptable for your application and medium. For polymer tubing: compatibility is conditional. Many polymers (e.g., PTFE, PEEK) may not provide the rigidity required for a reliable metal-to-metal ferrule seal; polymer tubes can deform and leak. If polymer tubing is used, confirm the polymerâs stiffness, pressure rating, and temperature limits match the fittingâs requirements. Often a specific backing support or different seal type is required; special elastomeric or face seals may be necessary depending on fluid, pressure and temperature. Always verify with the manufacturerâs detailed specifications and, if in doubt, use recommended seals or alternative fittings designed for polymer tubing and aggressive media.

Can the Straight fitting with GZ BSPT for metric tubing, brass, M768LR be used in high-temperature chemical processes and what temperature limits apply?

Straight fitting with GZ BSPT for metric tubing, brass, M768LR Format is intended for aggressive process industries, but its suitability for highâtemperature chemical processes is limited by the brass material and the tubing used. Brass maintains mechanical strength up to roughly 100â200 Â°C depending on alloy; continuous use above ~150 Â°C can degrade tensile strength and corrosion resistance, and above ~200 Â°C risk of annealing and softening increases. The allowable working pressure is set by tubing OD and wall thickness (see attachment) and must be derated for elevated temperature per applicable standards. For operations above ~150 Â°C or with aggressive/highly corrosive media, select a fitting/material certified for those conditions (e.g., stainless steel) or consult the manufacturer with exact temperature, pressure and chemical compatibility.

Does the Straight fitting with GZ BSPT for metric tubing, brass, M768LR support vacuum applications and what are the limits?

Straight fitting with GZ BSPT for metric tubing, brass, M768LR can be used in vacuum applications, but its suitability and limits depend on several factors. The fitting is a LET-LOKÂ® straight coupling with external BSPT thread for metric tubing, brass, intended for process industries. Key limitations: - Leak tightness: The brass LET-LOKÂ® design provides reliable metal-to-metal sealing on tubing; however, achieving high vacuum (deep vacuum) depends on assembly quality, surface finish, and proper tightening. For low vacuum or rough vacuum (down to ~10^-3 mbar) properly assembled fittings can often maintain acceptable leaks, but absolute performance must be verified for your system. - Allowable pressure rating: The provided allowable working pressure is determined by tubing outer diameter and wall thickness (see attachment). These ratings apply to positive pressure; for vacuum the tubing collapse (external pressure) and fitting joint integrity against external atmospheric pressure must be considered. Thin-walled tubing rated for high internal pressure may still collapse under vacuum if not designed for external pressure. - Temperature and media: Brass is suitable for many process media but may outgas or react in certain vacuum/chemical environments; check compatibility. Recommendations: 1. Verify the tubingâs collapse (external pressure) rating for the anticipated vacuum level using wall thickness and material properties. 2. Perform helium leak testing on assembled joints if you require high or ultra-high vacuum performance. 3. Ensure proper installation torque and clean, undamaged tube ends to maximize seal integrity. 4. For vacuum levels below ~10^-3 mbar or where permeation/outgassing is critical, consider fittings and materials specifically rated for high/ultra-high vacuum (e.g., stainless steel, metal-sealed flange technology). Conclusion: Straight fitting with GZ BSPT for metric tubing, brass, M768LR can support vacuum applications in many practical cases (rough to medium vacuum), but limits are set by tubing collapse strength, assembly quality, and leakage requirements; for high/ultra-high vacuum use, verify with leak testing or choose vacuum-specific fittings.

Fitting straight with male thread BSPT for a metric tube, brass, M768LR

All products, LET-LOK precision connectors/

Additional information

Material	B – brass (bronze)

A LET-LOK® straight fitting with a BSPT male thread for a metric tube intended mainly for the chemical, petrochemical and pharmaceutical industry, power generation, nuclear power plants and process engineering. The permissible working pressure is determined on the basis of the outer diameter and the wall thickness of the tube (details in the attachment). Material: brass.

List of product variants

Article number	Product variant name	DN	BAR	Availability	Actions
HM-LM768LR-03-02-B	Fitting for a tube 3 mm - 1/8" BSPT male, brass	-	-	In stock	Enquiry
HM-LM768LR-03-04-B	Fitting for a tube 3 mm - 1/4" BSPT male, brass	-	-	In stock	Enquiry
HM-LM768LR-06-02-B	Fitting for a tube 6 mm - 1/8" BSPT male, brass	-	-	In stock	Enquiry
HM-LM768LR-06-04-B	Fitting for a tube 6 mm - 1/4" BSPT male, brass	-	-	In stock	Enquiry
HM-LM768LR-06-06-B	Fitting for a tube 6 mm - 3/8" BSPT male, brass	-	-	In stock	Enquiry
HM-LM768LR-08-06-B	Fitting for a tube 8 mm - 3/8" BSPT male, brass	-	-	In stock	Enquiry

Do you need a larger quantity of products or a bespoke quote?

Call us: +48 61 653 02 22 or email us: tubes@tubes-international.com

SEND ENQUIRY

A LET-LOK® straight fitting with a BSPT male thread for a metric tube intended mainly for the chemical, petrochemical and pharmaceutical industry, power generation, nuclear power plants and process engineering. The permissible working pressure is determined on the basis of the outer diameter and the wall thickness of the tube (details in the attachment). Material: brass.