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Stainless Steel Instrumentation
Fractional / Metric Tubing
TS-04-S
2011
3 of 6
www.dklok.com4). System pressure
DK-LOK fitting pressure ratings are governed by the connective tubing pressure rating. To determine allowable working
pressure at elevated temperature, multiply the working pressure at ambient temperature shown in table 4 and 5 by the
factor shown in table 2.
Example:
SS316 seamless tubing 1/2 in. O.D. x 0.065
in.WTat 700 F. 4700 psig x 0.82 = 3854 psig.
Therefore 3854 psig is the maximum allowable working pressure at 700
o
F for SS316 seamless 1/2 in. O.D. x 0.065 in. wall thickness
tubing.
Table 2. Temperature De-rating Factors
Stainless steel
Temperature
ASTM A269
o
F
o
C
SS304
SS316
100
38
1
1
200
93
1
1
300
149
1
1
400
204
0.94
0.97
500
260
0.88
0.9
600
316
0.82
0.85
700
371
0.8
0.82
800
427
0.76
0.8
900
482
0.73
0.78
1000
538
0.69
0.77
1200
649
0.3
0.37
Table 3. Elastomer seal working temperature
When Elastomer seal is used in the system, care must be taken
for allowable working temperature. See Table 3.
Kalrez
®
: TM Dupont
5). Welded Tubing Working Pressure
As per ASME B31.3 Code for weld tubing working pressure, de-rating factors below must be applied.
For double butt weld tubing multiply by 0.85 and for single butt weld tubing multiply by 0.80.
Example:
SS316 single butt weld tubing 1/2 in. O.D. x 0.065 in. 4700 psig x 0.80 = 3760 psig at -20 to 100
℉
(-28 to 37
℃
).
6). Cryogenic Service
SS316 DK-LOK fittings provide highly reliable performance from cryogenic to high temperature.
SS316 DK-LOK fitting and tubing temperature Rating: -425 to 1200
℉
(-253 to 649
o
C)
Cryogenic temperature are considered temperatures below -100
℉
(-73
o
C)
Elastomer Seals
Working Temperature
NBR
-40 to 110C (-40 to 230
℉
)
FKM
-20 to 200
℃
(-4 to 392
℉
)
FFKM (Kalrez
®
)
-30 to 275
℃
(-22 to 527
℉
)