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As defined by the international ISO 10380-2012 standard, Maximum Allowable Working Pressure (MAWP) is the maximum pressure for which the hose assembly is designed. MAWP is specified by the manufacturer.

It is commonly accepted in our industry that the MAWP of an assembly should be no more than one-fourth of the burst pressure, or the pressure at which the assembly ruptures. This gives the assembly a safety factor of 4:1.

To establish Maximum Allowable Working Pressure, a straight hose assembly with a live length equal to ten (10) times its nominal diameter, but not less than twenty (20) inches, is subjected to gradually increasing hydrostatic pressure. The pressure at which the assembly ruptures is recorded as the burst pressure of the assembly.

To calculate a number for Working Pressure which we publish in our catalog, we would first apply the 4:1 safety factor mentioned above and then reduce the result by additional 20% to account for welding as the method of attachment.

The reason for this additional reduction is based on the fact that tensile strength of the braid wires located in the Heat Affected Zone (HAZ) might be affected by the heat and become lower.

An example

If the burst pressure of the hose was 1000 psi, the published MAWP calculated as the following:

1000 / 4 = 250 psi;

250 * 0.80 = 200 psi

For double-braided hoses, the MAWP published in our catalog is based on the addition of 60% to the number we published for single-braided hoses.

Therefore, if the single-braided hose assembly had a published WP of 1000 psi, then the MAWP of the double-braided hose would be calculated as:

1000 x 1.6 = 1600 psi

Note:

• MAWP published in our catalog is the maximum working pressure at 70°F. At elevated temperatures, the Temperature Adjustment Factor has to be applied. Please refer to our catalog for Adjustment Factors at different service temperatures.
• It is essential that the maximum operating pressure, including the surge pressure to which the hose is subjected in service, not exceed the specified Maximum Allowable Working Pressure.

Practical points to note:

• When making an assembly, it is important to make sure that braid is tight on the hose and all braid wires end flush with ends of hose.
• Testing has shown that the braid sleeves must be snug on the hose or the burst value of the hose will be significantly reduced.

For more information, please contact us.

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The Non-Destructive Testing Program (NDT) at Penflex is ASNT compliant and will offer these services to customers as well as perform customer requirements for NDT Inspections.

The program has three in house NDT Methods:

• Visual Inspection (VT)
• Liquid Penetrant Inspection (PT)
• Leak Test Inspection (LT)

SNT-TC-1A Level III oversight of the program’s Level II’s and testing techniques is part of that program. Two SNT-TC-1A Level II NDE’s are qualified in three methods of NDT Inspections as well as comply to ASME Section V Articles 6, 7, 9, and 10. Penflex has a LTA with an A2LA ISO 17025 Accredited Metallurgical testing lab and can provide those services as well.

In addition, Penflex has a Welding Program that includes ASME Section IX, PED 287-1, EN ISO 15614 Weld Procedure Qualifications with ISO 3834-2 Welding Coordination compliance in process.

The Welding Program includes full-time staff with in house CWI/CWE for continuous improvement of welding processes as well as ongoing development of Welding Matrixes formatted and maintained in an auditable position.

Developing and qualifying Welding Procedures in exotic alloys for customer’s requirements can now be done in house. Penflex’s CWI,CWE,NDE Level II Inspector has 35 years of experience in the Pressure Vessel, Piping, Structural, Fabrication and Welding industries.

Please contact us for further details on the Program or for pricing for Non-Destructive Testing services.