Typical applications would include building-services piping, potable water, fire protection, heating and cooling, industrial processes, process cooling and heating systems, plant utilities, and vacuum systems.
|Fig. 1: Pressfit joint|
Industry Specification, Codes and Product Testing
● Pressfit carbon steel products meet the requirements of ASTM A53 Grade A and A135 Grade A. Pressfit stainless steel products meet the requirements of ASTM A312 Grade 316/316L and ASTM A269 Grade 304/304L.
● Pressfit products meet the requirements for use in piping systems designed to comply with ASME B31.1, B31.3 and B31.9 piping codes. Pressfit products are qualified for use in these systems by the following paragraphs:
● International Conference of Building Official and Uniform Mechanical Code — UMC, ICBO-ES Report No. 5079
- Underwriters’ Laboratories—UL Listed
- Underwriters’ Laboratories Canada—ULC Listed
- Factory Mutual—FM Approval
- Southern Building Code Congress International, Public Safety Testing, Evaluation
- Service Inc.—SBCCI, PST, and ESI Report No. 9535
● Building Officials and Code Administrators—BOCA Evaluation Services Inc. Listed Report No. 93–3 Cat. 22 and Cat. 15
● National Fire Protection Association—NFPA 13
● Underwriters’ Laboratories—ANSI/NSF-61 listed for stainless steel potable water service
System Pressure and Temperature Rating
● Pressfit joints are rated for 300 psi (2065 kPa) when used in general service or process systems.
● Pressfit joints are rated for 175 psi (1200 kPa) for all fire protection services.
|Table A: Thermal service conditions|
|Fig. 2: 316/316L Stainless Steel PressFit|
|Fig. 3: Stainless Steel VIC-Press 304|
|Fig. 4: Carbon Steel PressFit|
|Table B: Pressfit insertion mark depth|
● System Support: Like all other piping systems, pipe joined with Pressfit joints requires support to carry the weight of the piping system, system fluid, and other system equipment. As in other methods of joining pipes, the support or hanging method must be adequate to eliminate undue stresses on joints, piping, and other system components. The suggested maximum span between supports for Pressfit piping systems is shown in Table C.
|Table C: Suggested maximum span between supports|
|Fig.5: Z-shaped expansion compensator|
|Fig. 6: U-shaped expansion compensator pipe with fittings|
|Fig. 7: Z-shaped expansion compensator Graph|
|Fig. 8: Z-shaped expansion compensator Graph|
Advantages of Pressfit
● Due to the design of the Pressfit fitting, piping designers can take advantage of the full-rated pressure capability of the Pressfit fitting across the allowed temperature range of the selected O-ring material. Pressure derating with an increase in metal temperature is not a factor in Pressfit systems as compared to a flanged system. Refer to Figs. 2, 3, and 4 for comparison.
● Pipe used in piping systems utilizing Pressfit joints has thinner nominal wall thickness than Schedule 40 pipe used in most applications where Pressfit should be considered. This difference results in significant increases of flow area and less pressure drop in Pressfit piping systems, compared to systems designed utilizing Schedule 40 pipe. A tabulation of these factors is shown in Tables D and E.
|Table D: Friction Loss|
|Table E: Flow Area|