Face Seal Fittings - VCR* Style Fittings

Truelok® offers a wide range of face seal fittings, mini weld & micro weld fittings and VCR* style fittings with surface finish down to 5 Ra, with or without electropolish. These fittings deliver outstanding performance in gas delivery systems and in the instruments to certify the purity of gases and the integrity of gas delivery system in the semiconductor industry. Truelok® fittings are interchangeable and intermixable with the fittings offered by other manufacturers. Truelok® specializes in producing high quality internal finish with Ra values less than 5. Our standard finish is 10 Ra. Several proprietary techniques have been developed for producing surface finish with low Ra values, proper surface chemistry, and high purity contamination-free components. A component’s surface finish is verified using profilometer and high-resolution microscopes are used to ensure a high luster finish.

Face Seal Fittings - Technical Information

Material Specification:

 Weld Fittings
 Micro Weld / Forged Weld Fittings
 Material Conforming Specifications


316L Stainless Steel 


   A182     A262     A269     A276

   A312     A351     A479     A484

   E112     E415   E1019    E1086

EN 1024 Type 3.1


 G4303  G3214  G5121  G345  G3463

 316L Stainless Steel VAR     


 Metal Face Seal Fittings
 Glands, Bodies  Gaskets 
 Material  Conforming Specifications   Material  Conforming Specifications
Stainless Steel


    A182     A262     A269     A276

    A312     A351     A479     A484

    E112     E415   E1019    E1086

 EN 1024 Type 3.1


  G4303  G3214  G5121  G345  G3463

 Nickel ASTM B162


Stainless Steel VAR 


Stainless Steel

ASTM B167 

Material Composition:

Chemistry of a few basic elements for comparison (Avg. Wt. %)

Element SS316L SS316L VAR SS316L VIM/VAR
Carbon 0.03 0.013 0.022
Sulphur 0.03 0.004 0.004
Manganese 2.00 1.520 1.290
Chromium 16.00-18.00 16.780 17.600
Nickel 10.00-14.00 10.250 13.180


Pressure Rating (SS 316L):

Working pressures are rated at ambient temperature and are based on a 4 to 1 design factor. To determine pressure ratings in accordance with ANSI B31.1 multiply pressure rating by 0.94.

Size Wall Thickness Pressure Rating
inch inch psig bar
1/8" 0.028 8500 586
1/4" 0.035 5200 359
3/8" 0.035 3350 231
1/2" 0.049 3750 259
3/4" 0.065 3350 231
1" 0.049 2400 165


Temperature Rating:

Products Material °F °C

Face Seal &

Mini Weld Fittings

SS316L 1000 538
SS316L VAR or VIM/VAR 1000 538
Face Seal Gaskets SS316L 1000 538
Nickel 600 316

Surface Finish:

Truelok® Face Seal & Mini Weld Fittings are offered in the following surface finishes:

Finish Electropolished Ra Value (Max) Ra Value (Avg)
Standard No 15 10
EP Yes 10 5


Electropolished Face Seal and Mini Weld Fittings:

Components are electropolished to provide oxide layer on the metal surfaces. This process prevents adsorption of gases and moisture on the surface to a greater degree and removes any contaminants adhered to the internal surface of the fittings. It also helps reduce friction and wear of the component. Moreover, due to enhanced smoothness of the electropolished wetted surface, build-up of products on the surface and any bacterial growth is reduced and provides with improved reflectivity of the finished surface.

Following is the surface analysis report of a typical Truelok® Electropolished face seal component:


Cr/Fe CrOX/FeOX Test Method
3.2 5.2 XPS Sematech Standard 90120403B


Silver Plated Nuts and Gaskets:


Threads of Female Nuts are silver plated to reduce the risk of galling and to improve re-make ability of the fitting. It also improves torque for the fitting assembly. Silver plated gaskets also reduce friction during assembly of fittings.

Cleaning and Packaging:

Ultra-High Purity cleaning and packaging in a Class 10 Clean Room environment validated per Federal Standard 209E, is standard for all electropolished components.



Truelok® face seal - VCR* style glands provide high integrity metal to metal seal, giving leak-tight service from vacuum to positive pressures (see pressure ratings). Such assemblies easily pass leak tests down to 1 x 10-9 std cm3/s.


The seal between two face seal glands is made when a gasket is placed between and compressed by the beads of the two glands during the engagement of a male nut or body hex and a female nut (see detailed instruction below).


Visual test and leak test are performed through two test ports in opposite locations from the female nut.


Face Seal Glands - VCR* Style Glands - Make-up Instructions:

  • Align the two sealing surfaces ensuring the toroid beads of the two glands squarely face each other.
  • Insert a VCR* Style metal gasket between the two toroids; if possible, use gasket with a retainer ring.
  • Tighten the female nut to the male nut/body finger tight.
  • Use two wrenches. Hold the male nut stationary with one wrench and tighten the female nut with the second wrench by 1/8 turn past finger tight.
  • Caution: Always torque the female nut while keeping male nut/body stationary.
  • Face Seal Connections are re-makable. However, use of a new gasket for each re-make is highly recommended. Face Seal Fittings need to be handled with great care until assembly and make-up. Sealing toroid of the glands are protected with caps, do not remove the caps until ready to make a seal. The sealing surfaces should never be scratched, damaged, or contaminated in any way during handling and assembly.

  • Always employ proper cleanroom protocol for make-up and assembly of high-purity fittings and applications.

*VCR is a registered trademark of Swagelok company, Truelok® is not affiliated with Swagelok company.