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Pressure Ratings For Tubing and Threaded End Connections

Stainless Steel Tubing Pressure Ratings Fractional Sizes - Table 1
Maximum Allowable Working Pressure (PSIG)

Tube O.D. Wall Thickness of Tube (inches)             
Size (Inches)   .010 .012 .014 .016 .020 .028 .035 .049 .065 .083 .095 .109 .120
1/16 5600 6850 8150 9500 12100                
1/8           8550 11000            
3/16           5450 7000 10300          
1/4           4000 5100 7500 10300        
5/16             4050 5850 8050        
3/8             3300 4800 6550        
1/2             2450 3500 4750 6250      
5/8               2950 4000 5200 6050    
3/4               2400 3300 4250 4950 5800  
7/8               2050 2800 3600 4200 4850  
1                 2400 3150 3650 4200 4700
1-1/4                   2450 2850 3300 3650
1-1/2                     2350 2700 3000
2                       2000 2200

 

Stainless Steel Tubing Pressure Ratings - Metric Sizes 
Maximum Allowable Working Pressure (Bar)

 Tube OD  Walll Thickness (mm) 
 Size (mm)  0.8 1 1.2 1.5 1.6 1.8 2 2.2 2.3 2.5 2.8 3 3.2 3.5 4 4.5 5
3 890                                
6 400 510 630 830 900                        
8 290 370 460 590 640                        
10 230 290 350 460 490 560 640                    
12 190 240 290 370 400 460 520                    
14   200 240 310 340 380 430 480                  
15   190 230 290 310 360 400 450 520                
16     210 270 290 330 370 410   480              
18     190 240 260 290 330 360   420              
20     170 210 230 260 290 320   370 420            
22     150 190 210 230 260 290   330 380            
25         180 200 230 250   290 330 350          
28         160   200 220   260 290 310   370      
30         150   190 210   240 270 290   340      
32         160   170 190   220 250 270   320 370    
38         110     160   180 210 220 240 260 300 350  
50                       170 170 200 230 260 290

Note: For welded and drawn tubing, a derating factor must be utilized. For double welded tube, multiply the above pressure rating by .85; and for single welded tube by .80 (ANSI B 31, Table A-1B). Suggested Tube Ordering Information: Specify the outside diameter and wall thickness of annealed, seamless or welded and drawn 316 or 304 stainless steel tubing of ASTM A-269, A-249, A-213 or equivalent. Also specify high quality tubing to be free of scratches, and suited for bending with material hardness not to exceed Rb 90.Calculation Basis: Annealed, seamless 304 or 316 stainless steel tubing ASTM A-269 or equivalent. System temperatures between -20°F and 100°F with allowable stress of 20,000 psi. Ultimate tensile strength of 75,000 psi. Safety factor of 4. Reference: ANSI B 31.3 Code. (For more specific working pressure information regarding a particular tubing, consult with the actual manufacturer of the tubing.)

Generally, SSP tube fittings, adapters and components (fittings) are rated for pressures equal to the maximum allowable working pressures of the tubing, hose or pipe recommended for use with the fittings. However, it is important to note that many specially designed fittings, bored-through fittings and fittings having SAE/AN, O-Ring boss and SAE/MS integral ends may have lower pressure ratings than that of the tubing.

Copper Tubing Pressure Ratings - Table 2

Maximum Allowable Working Pressure (PSIG)

Tube O.D. Wall Thickness of Tube (inches)             
Size (Inches)  .028 .035 .049 .065 .083 .095 .109 .120
1/8 2700 3600            
3/16 1700 2225 3450          
1/4 1250 1600 2475 3475        
5/16   1250 1900 2675        
3/8   1050 1550 2150        
1/2   750 1150 1550 2050      
5/8     900 1200 1600 1850    
3/4     700 1000 1275 1500 1775  
7/8     600 850 1075 1250 1500  
1     550 700 950 1100 1300 1400

Calculation Basis: Annealed (Temper 060), seamless copper tubing ASTM B-75 or equivalent. System temperatures between -20°F and 100°F with allowable stress of 6000 psi. Ultimate tensile strength of 30,000 psi. Safety factor of 5. Reference: ANSI B 31.3 Code. (For more specific working pressure information regarding a particular tubing, consult with the actual manufacturer of the tubing.)

Suggested Tube Ordering Information: Specify the outside diameter and wall thickness of annealed (Temper 060), seamless copper tubing of ASTM B-75, B-68, or equivalent specification. Also specify high quality tubing to be free of scratches, and suited for bending. Additionally acceptable: Annealed (Temper O) copper water tubing, Type K or Type L (ASTM B-88). No embossed markings allowed.

 

Alloy 400 Tubing Pressure Ratings - Table 4 

Maximum Allowable Working Pressure (PSIG)

Tube O.D. Wall Thickness of Tube (inches)             
Size (Inches)  .028 .035 .049 .065 .083 .095 .109 .120
1/8 8000 10450            
1/4 3750 4800 7000 9800        
3/8   3100 4450 6150        
1/2   2300 3300 4450        
3/4     2250 3050 4000 4600    
1       2250 2900 3400 3900 4350
 
 
Calculation Basis: Annealed, seamless Monel Alloy 400 tubing ASTM B-165 or equivalent. System temperatures between -20°F and 100°F with allowable stress of 18,700 psi. Ultimate tensile strength of 70,000 psi. Safety factor of 4. Table values are per the ANSI/ASME B 31.3 Code for temperatures from -325°F to only 100°F. Monel derates fast at elevated temperatures. (For more specific working pressure information regarding a particular tubing, consult with the actual manufacturer of the tubing.) Suggested Tube Ordering Information: Specify the outside diameter and wall thickness of annealed, seamless Monel Alloy 400 tubing of ASTM B-165 or equivalent specification. Also specify high quality tubing to be free of scratches, and suited for bending with material hardness not to exceed Rb 75.
 
 

NPT Pipe End Pressure Ratings, ANSI/ASME B 31.3 - Table 6

  316 Stainless Steel  Brass  Carbon Steel
NPT/ISO
Pipe Size
Size Male Female Male  Female  Male  Female
    psig bar psig bar psig bar psig bar psig bar
1/16" 1 11,050 760 6,750 460 3,350 230 11,050 760  6,750 460 
1/8" 2 10,050 690 6,550 450 3,250 220 10,050 690 6,550  450 
1/4" 4 8,050 550 6,650 460 3,350 230 8,050 5500 6,650  460 
3/8" 6 7,850 540 5,350 370 2,650 180 7,850 540 5,350  370 
1/2" 8 7,750 530 4,950 340 2,450 170 7,750 530 4,950  340 
3/4" 12 7,350 510 4,650 320 2,350 160 7,350 510 4,650  320 
1" 16 5,350 370 4,450 310 2,250 150 5,350 370 4,450  310 
1-1/4" 20 6,000 410 5,000 350 2,500 170 6,000 410 5,000  350 
1-1/2" 24 5,000 340 4,600 310 2,300 150 5,000 340 4,600  310 
2" 32 3,900 270 3,900 270 1,900 130 3,900 270 3,900  270 
Reference: bar = .0690 X psig  To obtain ANSI/ASME B 31.1 values, multiply ANSI/ASME B 31.3 values by .94

 

Pressure-Temperature Derating Table

Stress Factors For Determining Tubing Pressure Ratings at Elevated Temperatures

Instructions

To determine maximum allowable working pressures for tubing at elevated temperatures, multiply the applicable tube’s maximum allowable working pressure from Tubing Allowable Work Pressure Tables  by the corresponding temperature stress factor from Pressure-Temperature Derating Table below.

Duolok tube fittings function reliably in applications ranging from cryogenic temperatures to high temperature bake out with the tube fitting material as the limiting factor. It is important to note that elevated temperatures will reduce the maximum working pressure capability of the tubing system. (For more information regarding the effects of temperature on tubing pressure ratings, refer to Table 5 regarding temperature stress factors in SSP’s Selection Guide for Instrumentation Fittings and Tubing).

Temperature Stainless Steel   CarbonSteel  Copper  Monel®400
°F °C 304SS 316SS      
    100
38
    1.00
    1.00
            1.00
     1.00
1.00
200 93 1.00 1.00 .96 .80 .88
300 149 1.00 1.00 .90 .78 .82
400 200 .94 .97 .86 .50 .79
500 260 .88 .90 .82 n/a .79
600 316 .82 .85 .77 n/a .79
700 371 .80 .82 .73 n/a .79
800 427 .76* .80* .59 n/a .76
900 482 .73* .78* .41 n/a .43
1000 538 .69* .73* .16 n/a n/a
1200 649 .30* .37 n/a n/a n/a

* The precipitation of chromium carbides potentially resulting in intergranular corrosion may occur when exposed to operating temperatures above 800°F. Consult the factory for further information.