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Appendix C VCR and Swagelok Fittings 89
3. Hold the fitting body steady with a
backup wrench and tighten this nut 1¼
turns. Watch the scribe mark, making
one complete revolution and continue to
the 9 o’clock position.
By scribing the nut at the 6 o’clock position
as it appears to you, there will be no doubt
as to the starting position. When the nut is
tightened 1¼ turns to the 9 o’clock position,
you can easily see that the fitting has been
properly tightened.
Use of the Gap Inspection Gauge (1¼ turns
from finger-tight) ensures sufficient pull-up.
Notes:
1. For 1/16, 1/8, 3/16, 2 mm, 3 mm and
4 mm size tube fittings, only ¾ turn
from finger tight is necessary.
2. A Swagelok Hydraulic Swaging unit
must be used for assembly of Swagelok
Tube Fittings onto 1¼, 1½, 2, 28
mm, 32 mm, and 38 mm outside
diameter steel and stainless steel
tubing.
High Pressure Applications
or High-Safety-Factor Systems
Due to variations in tubing diameters, a common starting point is desirable. Using a
wrench, tighten the nut to the SNUG position. Snug is determined by tightening the nut
until the tubing will not rotate freely (by hand) in the fitting. If tube rotation is not
possible, tighten the nut approximately 1/8 turn from the finger-tight position. At this
point, scribe the nut at the 6 o’clock position and tighten the nut 1¼ turns. The fitting
will now hold pressures well above the rated working pressure of the tubing.
Retightening Instruction
Connections can be disconnected and retightened many times. The same reliable leak-
proof seal can be obtained every time the connection is remade. Directions follow.
1. Fitting shown in the disconnected position
2. Insert tubing with preswaged ferrules into
fitting body until front ferrule seats.
3. Tighten nut by hand. Rotate nut to the original
position with a wrench. An increase in
resistance will be encountered at the original
position.
Then tighten slightly with the wrench. Smaller tube sizes will take less tightening to
reach the original position, while larger tube sizes will require more tightening. The wall
thickness will also have an effect on tightening.