ASME External Pressure Question

• IN617 is not an ASME nor an ASTM material.

• Operating temp. 700 ^oC means you have to use a design temp. say 900 ^oC, and that is very high temp. which you have to proceed a special considerations while design and selection of material.

• May be your carbon steel or low alloy steel (Charts Fig. CS & HT) are not sufficient to overcome the design (not only operating) conditions and you need a high alloy material, and hence you can use the chart of ASME BPVC, Section II, Part D, FIG. HA-2 (CHART FOR DETERMINING SHELL THICKNESS OF COMPONENTS UNDER EXTERNAL PRESSURE DEVELOPED FOR AUSTENITIC STEEL 16Cr–12Ni–2Mo, TYPE 316), which indicates a design temp. up to 1500 ^oF (815 ^oC) for that material with E = 18.1X10⁶ PSI.

Fig. HA-2

• Also make a check for selection of a material belong to chart Fig. HA-1.

Thank you for the reply. IN617 is actually an ASME as well as an ASTM material; the exact designation of the material is Inconel 617 (UNS N06617) and it is listed in Section II, Part D of the ASME B&PV code.

Stainless steel won't do it in my application because the required wall thickness will be too large. Now that you know the exact designation of the material, will you be able to offer any help? I appreciate your input.

OP

Inconel products have a special properties and higher specifications, and are not recognized as ASME or ASTM materials. All inconel products have a special designation differs from ASME and ASTM, e.g. INCONEL® alloy 617.

For inconel products, see CR4 Thread Incoloy 800H & Inconel 601 materials, post #5.

By searching in ASME BPVC, Section II, Part D, for the material Inconel 617 by its UNS N06617, we found that the following ASME materials have the same UNS N06617: ASME SB 166 (bar & rod), SB 167 (smls pipe & tube), SB 168 (plate, sheet & strip), and SB 564 (forgings), and all of those ASME materials are annealed and belong to external pressure chart Fig. NFN-4 (see ASME BPVC, Section II, Part D, Table 1B & Fig. NFN-4).

So, you can use the following external pressure chart Fig. NFN-4, which includes curves with design temp. up to 1200 ^oF (649 ^oC), which is still below 700 ^oC:

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I ask yours to read the brochure of INCONEL® alloy 617, which contains:

Allowable design stresses for INCONEL alloy 617 products are found in Table 1B of Section II, Part D of the ASME Boiler andP ressure Vessel Code. Alloy 617 is one of the few materials covered by the ASME Code with design stresses up to 1800 °F (982 ^oC). Allowable design stresses from the 2005 edition for the common temperatures of application are compared with those for UNS N06230 in Table 8. It is seen that alloy 617 permits increasingly higher design stresses over UNS N06230 as temperature increases in the range where these alloys are typically employed.

Hello Abdel Halim Galala,

Thank you for your help. I guess now you understand my dilemma. In Table 1B, the allowable stresses for Inconel 617 are listed up to a maximum temperature of 900 degC, but on the external pressure chart NFN-4, the stresses are listed only up to a temperature of 650 degC. Now, the question is how I can get the external pressure stress values for temperatures higher than 650 degC.

OP