pressure storage sphere manufacturing  shop testing

9. SITE ERECTION

9.1 Site erection of Pressure Storage Spheres shall be in accordance with Iranian Petroleum Standard xxxx  ”Construction Standard for Pressure Storage Spheres ( For LPG )”.

9.2 The shell of a completed pressure storage sphere shall be substantially round and the difference between the maximum and minimum inside diameter at any cross section shall not exceed 1% of the nominal diameter at the cross section under consideration.

10. INSPECTION AND TEST

10.1 The inspection and testing for pressure storage spheres shall conform to Asme Code Section VIII, Pressure Vessels.

10.2 The latest edition of the following Sections of ASME Code shall be used in conjunction with this Standard:

a) ASME Code Section V “Non-destructive Examination”.

b) ASME Code Section IX “Welding Qualifications”.

10.3 Pressure storage spheres shall be designed on the basis of spot radiographic examination by ASME Code Section VIII as a minimum.

10.4 Plates to be used for pressure retaining parts in wet H2S service shall be ultrasonically tested in accordance with ASTM A 578, acceptance level 1.

10.5 When required by ASME Code Section VIII, charpy impact tests shall be made on weldments and all materials for shell heads, nozzles and all parts subject to stress due to pressure.

10.6 Inspection of Shell Joints 10.6.1 Unless otherwise specified pressure storage spheres shell joints shall be spot radiographed.

10.6.2 Method and acceptance standard for spot radiography shall be in accordance with para. UW- 52 and those for 100% radiography shall be in accordance with para. UW-51 of ASME Code Section VIII, Div. 1.

10.6.3 A minimum of one spot radiograph shall be taken at each weld intersection and in the case of spheres, one in each vertical (meridional) weld seam.

10.6.4 Shell plate seams which are not stressed to at least the design stress in the corroded condition during the hydrostatic test, shall be subjected to 100% radiographic examination.

10.6.5 Shell seams covered by a nozzle reinforcing pad or any other structural overlay shall be spot radiographed in the portion covered.

10.6.6 Radiographic film shall be equivalent to type 1 or 2 per ASTM E 94 and film length shall be 254 mm minimum.

10.6.7 Where the material having a specified ultimate tensile strength of 50 kgf/mm2 and over or pressure storage spheres are designed with full radiographic examination, the back gouged surface shall be ground to the bright metal and fully examined by the use of magnetic particle or liquid penetrant examination method.

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