stresses created by bending and forming. Provisions in
para. 331 are basic practices which are suitable for
most welding, bending, and forming operations, but
not necessarily appropriate for all service conditions.
331.1 General
331.1.1 Heat Treatment Requirements
(a) Heat treatment shall be in accordance with the
material groupings and thickness ranges in Table 331.1.1
except as provided in paras. 331.2.1 and 331.2.2.
(b) Heat treatment to be used after production welding
shall be specified in the WPS and shall be used
in qualifying the welding procedure.
(c) The engineering design shall specify the examination
and/or other production quality control (not less
than the requirements of this Code) to ensure that the
final welds are of adequate quality.
(d) Heat treatment for bending and forming shall be
in accordance with para. 332.4.
331.1.3 Governing Thickness. When components
are joined by welding, the thickness to be used in
applying the heat treatment provisions of Table 331.1.1
shall be that of the thicker component measured at the
joint, except as follows.
(a) In the case of branch connections, metal (other
than weld metal) added as reinforcement, whether an
integral part of a branch fitting or attached as a reinforcing
pad or saddle, shall not be considered in determining
heat treatment requirements. Heat treatment is required,
however, when the thickness through the weld in any
plane through the branch is greater than twice the
minimum material thickness requiring heat treatment,
even though the thickness of the components at the
joint is less than the minimum thickness. Thickness
through the weld for the details shown in Fig. 328.5.4D
shall be computed using the following formulas:
sketch (1) p T b + tc
sketch (2) p T h + tc
sketch (3) p greater of T b + tc or T r + tc
sketch (4) p T h + T r + tc
sketch (5) p T b + tc
(b) In the case of fillet welds at slip-on and socket
welding flanges and piping connections DN 50 (NPS
2) and smaller, for seal welding of threaded joints in
piping DN 50 and smaller, and for attachment of
external nonpressure parts such as lugs or other pipe
supporting elements in all pipe sizes, heat treatment is
required when the thickness through the weld in any
plane is more than twice the minimum material thickness
requiring heat treatment (even though the thickness of
the components at the joint is less than that minimum
thickness) except as follows:
(1) not required for P-No. 1 materials when weld
throat thickness is 16 mm (5⁄8 in.) or less, regardless
of base metal thickness;
(2) not required for P-No. 3, 4, 5, or 10A materials
when weld throat thickness is 13 mm (1⁄2 in.) or less,
regardless of base metal thickness, provided that not
less than the recommended preheat is applied, and the
specified minimum tensile strength of the base metal
is less than 490 MPa (71 ksi);
(3) not required for ferritic materials when welds
are made with filler metal which does not air harden.
Austenitic welding materials may be used for welds
to ferritic materials when the effects of service conditions,
such as differential thermal expansion due to
elevated temperature, or corrosion, will not adversely
affect the weldment.
331.1.4 Heating and Cooling. The heating method
shall provide the required metal temperature, metal
temperature uniformity, and temperature control, and
may include an enclosed furnace, local flame heating,
electric resistance, electric induction, or exothermic
chemical reaction. The cooling method shall provide
the required or desired cooling rate and may include
cooling in a furnace, in air, by application of local
heat or insulation, or by other suitable means.
CHAPTER VI
INSPECTION, EXAMINATION, AND TESTING
340 INSPECTION
340.1 General
This Code distinguishes between examination (see
para. 341) and inspection. Inspection applies to functions
performed for the owner by the owner’s Inspector or
the Inspector’s delegates. References in this Code to
the “Inspector” are to the owner’s Inspector or the
Inspector’s delegates.
340.2 Responsibility for Inspection
It is the owner’s responsibility, exercised through
the owner’s Inspector, to verify that all required examinations
and testing have been completed and to inspect
the piping to the extent necessary to be satisfied that
it conforms to all applicable examination requirements
of the Code and of the engineering design.
340.3 Rights of the Owner’s Inspector
The owner’s Inspector and the Inspector’s delegates
shall have access to any place where work concerned
with the piping installation is being performed. This
includes manufacture, fabrication, heat treatment, assembly,
erection, examination, and testing of the piping.
They shall have the right to audit any examination, to
inspect the piping using any examination method specified
by the engineering design, and to review all
certifications and records necessary to satisfy the owner’s
responsibility stated in para. 340.2.
340.4 Qualifications of the Owner’s Inspector
(a) The owner’s Inspector shall be designated by
the owner and shall be the owner, an employee of the
owner, an employee of an engineering or scientific
organization, or of a recognized insurance or inspection
company acting as the owner’s agent. The owner’s
Inspector shall not represent nor be an employee of
the piping manufacturer, fabricator, or erector unless
the owner is also the manufacturer, fabricator, or erector.
(b) The owner’s Inspector shall have not less than
10 years experience in the design, fabrication, or inspec-
tion of industrial pressure piping. Each 20% of satisfactorily
completed work toward an engineering degree
recognized by the Accreditation Board for Engineering
and Technology (Three Park Avenue, New York, NY
10016) shall be considered equivalent to 1 year of
experience, up to 5 years total.
(c) In delegating performance of inspection, the owner’s
Inspector is responsible for determining that a
person to whom an inspection function is delegated is
qualified to perform that function.
341.1 General
Examination applies to quality control functions performed
by the manufacturer (for components only),
fabricator, or erector. Reference in this Code to an
examiner is to a person who performs quality control
examinations.
341.2 Responsibility for Examination
Inspection does not relieve the manufacturer, the
fabricator, or the erector of the responsibility for:
(a) providing materials, components, and workmanship
in accordance with the requirements of this Code
and of the engineering design [see para. 300(b)(3)];
(b) performing all required examinations; and
(c) preparing suitable records of examinations and
tests for the Inspector’s use.
341.3 Examination Requirements
341.3.1 General. Prior to initial operation each piping
installation, including components and workmanship,
shall be examined in accordance with the applicable
requirements of para. 341. The type and extent of
any additional examination required by the engineering
design, and the acceptance criteria to be applied, shall
be specified. Joints not included in examinations required
by para. 341.4 or by the engineering design are
accepted if they pass the leak test required by para. 345.
(a) For P-Nos. 3, 4, and 5 materials, examination
shall be performed after completion of any heat
treatment.
(b) For a welded branch connection the examination
of and any necessary repairs to the pressure containing
weld shall be completed before any reinforcing pad or
saddle is added.
341.3.2 Acceptance Criteria. Acceptance criteria
shall be as stated in the engineering design and shall
at least meet the applicable requirements stated below,
in para. 344.6.2 for ultrasonic examination of welds,
and elsewhere in the Code.
(a) Table 341.3.2 states acceptance criteria (limits
on imperfections) for welds. See Fig. 341.3.2 for typical
weld imperfections.
(b) Acceptance criteria for castings are specified in
para. 302.3.3.
341.3.3 Defective Components and Workmanship.
An examined item with one or more defects (imperfections
of a type or magnitude exceeding the acceptance
criteria of this Code) shall be repaired or replaced; and
the new work shall be reexamined by the same methods,
to the same extent, and by the same acceptance criteria
as required for the original work.
341.3.4 Progressive Sampling for Examination.
When required spot or random examination reveals a
defect:
(a) two additional samples of the same kind (if
welded or bonded joints, by the same welder, bonder,
or operator) shall be given the same type of examination;
and
(b) if the items examined as required by (a) above
are acceptable, the defective item shall be repaired or
replaced and reexamined as specified in para. 341.3.3,
and all items represented by these two additional samples
shall be accepted; but
(c) if any of the items examined as required by (a)
above reveals a defect, two further samples of the same
kind shall be examined for each defective item found
by that sampling; and
(d) if all the items examined as required by (c)
above are acceptable, the defective item(s) shall be
repaired or replaced and reexamined as specified in
para. 341.3.3, and all items represented by the additional
sampling shall be accepted; but
(e) if any of the items examined as required by (c)
above reveals a defect, all items represented by the
progressive sampling shall be either:
(1) repaired or replaced and reexamined as required;
or
(2) fully examined and repaired or replaced asnecessary, and reexamined as necessary to meet the
requirements of this Code.
341.4 Extent of Required Examination
341.4.1 Examination Normally Required. Piping
in Normal Fluid Service shall be examined to the extent
specified herein or to any greater extent specified in
the engineering design. Acceptance criteria are as stated
in para. 341.3.2 and in Table 341.3.2, for Normal Fluid
Service unless otherwise specified.
(a) Visual Examination. At least the following shall
be examined in accordanc