Pipe & Stainless Steel Tubing Pressure Ratings

Pressure Ratings For Tubing and Threaded End Connections

Generally, 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.  Pressure ratings for fittings with both tube fitting and pipe thread ends are determined by the end connection with the lower pressure rating. Female and male pipe threads to have the same pressure rating in the same nominal pipe size.  However to achieve the same pressure rating as the male pipe end, female ends require a heavier wall than practical. Note that many specially designed fittings, bored-through fittings and fittings having AN, O-Seal and SAE/MS integral ends may have lower pressure ratings than that of the tubing. For more precise pressure ratings for a specific fitting, contact Neelcon customer service.  

Stainless Steel Tubing Pressure Ratings, Fractional Sizes

Notes: 1) Shaded areas indicate tubing that is not suitable for gas service. 2) For welded and drawn tubing, a derating factor must be utilized. For double welded tube, multiply the below pressure rating by 0.85; and for single welded tube by .80 (ANSI B 31, Table A-1B).

Stainless Steel Tubing Pressure Ratings - Metric Sizes 

Copper Tubing Pressure Ratings 

Maximum Allowable Working Pressure (PSIG)

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. Reference: ANSI B 31.3 Code. (For more specific working pressure information regarding a particular tubing, consult with the actual manufacturer of the tubing.)

Alloy 400 Tubing Pressure Ratings 

Maximum Allowable Working Pressure (PSIG)

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. 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/ISO Pipe End Pressure Ratings, ANSI/ASME B 31.3 

Pressure-Temperature Derating Table

Stress Factors for Determining Tube Pressure Ratings at Elevate 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.

Neelcon 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 Neelcon’s Selection Guide for Instrumentation Fittings and Tubing).

* 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.