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ASME Sec. II; Materials; Parts A, B, C, D

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ASME Section II is divided into four parts covering the materials for the construction of piping and pressure vessels.

Part A: Ferrous Material Specifications.  This part contains the individual specifications for  ferrous  materials  that  are  allowed  in  the  construction  of  pressure  vessels  and  piping designed  according to  the  ASME  BPVC.  Part  A  covers  all  forms  of  ferrous  material  products  like wrought,  castings,  forgings,  plates,  piping  valves,  bolting,  etc.

The  topics  addressed  for each  ferrous  material  specification  vary  based  on  the  characteristics  of  the  material  and the intended usage.  Some examples of topics covered include:

  • Ordering information,
  • Heat treatment,
  • Chemical composition,
  • Mechanical properties,
  • Tests and examinations,
  • Dimensions and  tolerances  and
  • Steel making practice.

 

The inspector should be familiar with the contents of whichever materials are specified in the contractual agreements.

 

Below specifications covered in ASME Section II, Part A and is particularly important:

 

SA-20, General Requirements for Steel Plates

Laminations visible on the edge of plate ≥1” is acceptable.

Weld repair of plates shall be done only with approval of purchaser and with a qualified WPS as per ASME IX.

Thicker plates have inherent lower elongations.

Each set of charpy test has 3 specimens.

Makings for plates over ¼ “shall be by die stamping and less than ¼ “by painting.

Table 1 shows the limit on elements.

Table 2 shows the carbon equivalent versus thickness and strength. For example, if the plate strength is between 60-70 ksi, the maximum carbon equivalent is 0.45 for less than 2” and 0.46 for over 2”. For higher strength and/or thickness, higher carbon equivalent is allowed for weldability purpose.

 

Tables 3 &4 show maximum deviation from flatness versus thickness and width for carbon steel.

 

Tables 5 & 6 show maximum deviation from flatness versus thickness and width for low alloy steel.

 

Carbon equivalent (CE) shall be calculated by the following formula:

ASME Sec. II; Materials; inspector-training

The steel shall have a maximum sulfur of 0.010%.

 

Table A.1.1 shows permissible variation versus thickness and width.

 

Other tables include permissible variation in width, length, diameter, waviness.

 

Table A2.15 shows the charpy test acceptance criteria (for average and minimum for 1 specimen) for various grades & class versus thickness & test temperature.

 

SA-370, Test Methods and Definitions of Mechanical Testing Steel Products

The terms “longitudinal test” and “transverse test” are used only in material specifications for wrought products and are not applicable to castings.

 

Wrought steel products are usually tested in the longitudinal direction, but in some cases, where size permits and the service justify it, testing is done in the transverse direction as well.

 

Aging of Test Specimens: may be accomplished by aging the sample at room temperature for 24 – 48 hours, or in shorter time at moderately elevated temperatures by boiling in water, heating in oil or in an oven. It is like baking before testing.

 

Yield Point: Yield point is the first stress in a material, excluding the maximum obtainable stress (ultimate stress), at which an increase in strain occurs without an increase in stress.

The stress-strain diagram is characterized by a sharp knee or discontinuity.

ASME Sec. II; Materials; inspector-training

BEND TEST: is a qualitative test and NOT quantitative. The severity of the bend test is primarily a function of the angle of bend, inside diameter to which the specimen is bent, and the specimen cross section.

ASME Sec. II; Materials; inspector-training

Hardness Test: is to determine resistance to penetration and is occasionally employed to obtain a quick approximation of tensile strength.

353 HB (38 HRC) means that a hardness value of 38 was obtained using the Rockwell C scale and converted to a Brinell hardness of 353.

 

Brinell Test: A specified load is applied to a flat surface of the specimen to be tested, through a hard ball of specified diameter. The average diameter of the indentation is used as the basis for calculation of Brinell hardness number.

ASME Sec. II; Materials; inspector-training

Charpy Impact Test: a notched specimen is struck and broken by a single blow and the measured test values may be the energy absorbed.

 

Minimum 3 charpy impact specimens shall be tested from a single location.

 

The test is normally done at the minimum design metal temperature or colder.

 

The charpy test is accepted if the average of 3 specimens is equal or more than minimum specified and no single specimen is less than 2/3 of average minimum.

ASME Sec. II; Materials; inspector-training

Typical Destructive Tests (tensile, bend, impact)

ASME Sec. II; Materials; inspector-training

SA-6, Thickness Tolerances for Steel Plate

When heats of the same nominal chemical composition are consecutively cast at one time, the heat number assigned to the cast product need not be changed.

 

For each heat, the heat analysis shall include determination of the content of carbon, manganese, phosphorus, sulfur, silicon, nickel, chromium, molybdenum, copper, vanadium, columbium (niobium)

 

For each heat, the purchaser shall have the option of analyzing representative samples taken from the finished structural product.

 

TABLE A shows Permitted Variations in Product Analysis for various elements (carbon, manganese, phosphorus, sulfur, silicon, nickel, chromium, molybdenum, copper, vanadium, columbium).

 

The grinding of plate should not reduce the thickness of the plate by (1) more than 7 % under the nominal thickness for plates ordered to weight per square foot or mass per square meter, but in no case more than 1⁄8” [3 mm]; or below the permissible minimum thickness for plates ordered to thickness in inches or millimeters.

Minimum of 2 Tension Tests is required per Heat (Table B).

 

Marking:

  • applicable ASTM designation;
  • G (for untreated) or MT (for heat treated);
  • applicable grade; heat number;
  • size and thickness;
  • Name, brand, or trademark of the manufacturer.

 

 

The required markings for plates shall be in at least one place on each finished plate.

ASME Sec. II; Materials; inspector-training

ASME Sec. II; Materials; inspector-training

 

Table 1 Permitted Variations in Thickness

Table 2 Permitted Variations in Weight

Table 3 Permitted Variations in Width and Length

 

Part B: Nonferrous Material Specifications.  This  part  contains  the  individual specifications  for  nonferrous  materials  that  are  allowed  in  the  construction  of  pressure vessels  and  piping  designed  to  the  ASME.

 

Part  B  covers  all  forms  of  nonferrous material  products  like  wrought,  castings,  forgings,  plates,  piping  valves,  bolting,  etc. allowed for in the construction of ASME equipment. The types of nonferrous material alloys included in Part B are: aluminum, copper, nickel, titanium, and zirconium.

 

The topics addressed by  each nonferrous material specification  vary based on the characteristics of the  material  and  final  use  for  which  it  is  intended.  Some  examples  of  issues  covered include: ordering information, heat treatment, chemical composition, mechanical properties, tests  and  examinations,  dimensions  and  tolerances  and  the  steel  making  practice.

 

The inspector should be familiar with the contents of whichever materials are specified in the contractual agreements.  However  there  will  be  no  specific  questions  on  the  core examination out of Part B, but the SI should be familiar with what the standard covers.

 

Part C:  Specifications for Welding Rods, Electrodes and Filler Metals.

 

Part C covers material  specifications  for  the  manufacture,  acceptability,  chemical  composition, mechanical  usability,  surfacing,  testing,  operating  characteristics  and  intended  uses  of welding rods, electrodes and filler materials. The material specifications are designated by SFA numbers derived from AWS specifications.

 

The  inspector  would  typically reference  these  specifications  for  whichever  welding  materials  are  specified  in  the contractual  agreements  to  ensure  that  the  right  materials  are  being  used  in  fabrication.

Part D: Materials Properties.  Part  D  provides  tables  for  design  stress  values,  tensile strength,  yield  strength,  and  other  important  chemical  and  physical  properties  for  all  the material  specifications  contained  in  Parts  A  and  B.

 

This section is primarily intended for designers of ASME equipment.

 

 

 

 

 

 

 

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