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DEFINITIONS
PWHT means “POST WELD
HEAT TREATMENT” This is done to remove residual stress
left in the joint which may cause brittle fracture
Strength: Strength is defined as,
“the ability of a material to withstand
an applied load.”
Ductility: Ductility is a term
which relates to the ability of a material
to deform, or stretch, under load
without failing.
Hardness: Hardness
is the ability of a metal to resist penetration or indentation.
Toughness: Toughness
is the ability of a material to absorb energy.
FATIGUE STRENGTH
The
relative ability of a metal to withstand cyclic loading, as in stress reversal
HAZ
HEAT-AFFECTED
ZONE ; the metal adjacent to a weld that does not melt but is affected by the
heat
of welding.
NORMALIZING
A
heat treatment whereby steel is heated into the austenite range and cooled in
still air
QUENCHING
In
heat treatment, very rapid cooling from elevated temperatures.
TEMPERING
A
heat treatment which reduces the strength and hardness of as-quenched steels
and restores ductility
& toughness
DEFECT
A
discontinuity which exceeds the permissible limit of a code; a rejectable
discontinuity requiring
repair or replacement
DISCONTINUITY
Any irregularity in the normal pattern of a
material; any interruption of the uniform nature of an item.
DCEN
Direct current, electrode negative.
Referred to as straight polarity
DCEP
Direct current, electrode positive.
Referred to as reverse polarity.
CODE
A body of laws,
as of a nation, city, etc., arranged systematically for easy reference.
ESSENTIAL VARIABLES (Procedure)
A
change in a welding condition which will affect the mechanical properties
(other than notch
toughness) of the weldment (e.g.,
change in P-Number, welding process, filler metal,
electrode, preheat or postweld
heat treatment).
ESSENTIAL VARIABLES (Performance)
A change in a welding condition which will affect the ability of a
welder to deposit sound weld
metal (such as a change
in welding process, deletion of backing, electrode, F-Number,
technique,etc.).
SUPPLEMENTARY ESSENTIAL VARIABLES
Supplementary essential variables are
required for metals for which other Sections specify
notch-toughness tests
and are in addition to the essential variables for each welding process.
NONESSENTIAL VARIABLES
Nonessential variables are those in which a change, as described
in the specific variables,
may be made in the WPS
without requalification.
WELDING
A
joining process that produces coalescence of materials by heating them to the
welding temperature, with or without the application of pressure or by the
application of pressure alone, and with or without the use of filler
metal.
WELDABILITY
The capacity of
material to be welded under the imposed fabrication conditions into a
specific,
suitably designed structure
and to perform satisfactorily in the intended service.
PROCEDURE
QUALIFICATION RECORD (PQR).
A record
of welding variables used to produce an acceptable test
weldment and the results of tests conducted on the
weldment to qualify a welding procedure specification.
(or)
Procedure Qualification Record (PQR). A PQR is a record of the welding data used to weld a test coupon.
The
PQR is a record of variables recorded during the welding of the test coupons.
It also contains the test results
of
the tested specimens.
WELDING
PROCEDURE SPECIFICATION (WPS).
A document
providing the required welding variables for a specific application to assure
repeatability by properly trained welders and welding operators.
(or)
A WPS is a written qualified welding procedure prepared to provide
direction for making production welds to Code requirements.
ASME B31.3-2010 Code Requirement
ASME B31.3 -2010 RQUIREMENTS
fluid service: a general term concerning the
application of a piping system, considering the combination of fluid properties,
operating conditions, and other factors that establish the basis for design of
the piping system. See Appendix M.
(a) Category D Fluid Service: a fluid service in
which all the following apply: (1) the fluid handled is nonflammable,
nontoxic, and not damaging to human tissues as defined in para. 300.2 (2) the design gage
pressure does not exceed 1035 kPa (150 psi). (3) the design temperature is from −29°C
(−20°F) through 186°C (366°F).
(b) Category M Fluid Service: a fluid service in
which the potential for personnel exposure is judged to be significant and in
which a single exposure to a very small quantity of a toxic fluid, caused by
leakage, can produce serious irreversible harm to persons on breathing or
bodily contact, even when prompt restorative measures are taken.
(c) Elevated Temperature Fluid Service: a fluid service in
which the piping metal temperature has a design or sustained operating
temperature equal to or greater than Tcr as defined in Table 302.3.5, General
Note (b).
(d) High Pressure Fluid Service: a fluid service for which
the owner specifies the use of Chapter IX for piping design and construction;
see also para. K300.
(e) Normal Fluid Service: a fluid service
pertaining to most piping covered by this Code, i.e., not subject to the rules
for Category D, Category M, elevated temperature, or High Pressure Fluid
Service.
(f ) High Purity Fluid Service: a fluid service that requires
alternative methods of fabrication, inspection,
examination, and testing not covered elsewhere in the Code,
with the intent to produce a controlled level of cleanness.
The term thus applies to piping systems defined for other
purposes as high purity, ultra-high purity, hygienic, or aseptic.
severe cyclic conditions: conditions applying
to specific piping components or joints in which SE computed in accordance with para.
319.4.4 exceeds 0.8SA (as defined in para. 302.3.5), and the equivalent
number of cycles (N in para. 302.3.5) exceeds 7000; or other conditions that
the designer determines will produce an equivalent effect.
For PWHT
Requirement
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:
(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 non
pressure 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 material, 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.
a) Annealing: heating to and holding at a suitable
temperature and then cooling at a suitable rate for such purposes as: reducing
hardness, improving machinability, facilitating cold working, producing a
desired microstructure, or obtaining desired mechanical, physical, or other
properties.
(b) Normalizing: a process in which a ferrous metal
is heated to a suitable temperature above the transformation
range and is subsequently cooled in still air at room temperature.
(c) Preheating: the application of heat to the base
material immediately before or during a forming, welding, or cutting process.
See para. 330.
(d) Quenching: rapid cooling of a heated metal.
(e) Recommended or required heat treatment: the application of
heat to a metal section subsequent to a cutting, forming, or welding operation, as
provided in para. 331.
(f) Solution heat treatment: heating an alloy to a
suitable temperature, holding at that temperature long enough to allow one or
more constituents to enter into solid solution, and then cooling rapidly enough
to hold the constituents in solution.
(g) stress-relief: uniform heating of a structure or
portion thereof to a sufficient temperature to relieve the major portion of the
residual stresses, followed by uniform cooling slowly enough to minimize
development.
(h) Tempering: reheating a hardened
metal to a temperature below the transformation range to improve toughness.
(i) Transformation range: a temperature range
in which a phase change is initiated and completed.
(j) Transformation temperature: a temperature at
which a phase change occurs of new residual stresses.
ASME SEC IX REQUIREMENTS
QW-200.1A (a) Welding Procedure Specification
WPS is a written qualified welding procedure prepared to
provide direction for making production welds to Code requirements.
QW-200.2 (a) Procedure Qualification Record
A PQR is a record of the welding data used to weld a test
coupon. The PQR is a record of variables recorded during the
welding of the test coupons. It also contains the test
results of the tested specimens. Recorded variables normally fall
within a small range of the actual variables that will be
used in production welding.
.
Welder Performance Qualification Test: The performance
qualification tests are intended to determine the ability of welders and
welding operators to make sound welds.
A welder or welding operator may be qualified by
radiography of a test coupon, radiography of his initial production
welding, or by bend tests taken from a test coupon except
as stated in QW-304 and QW-305.
QW-304 Welders
A welder qualified to weld in accordance with one
qualified WPS is also qualified to weld in accordance with other
qualified WPSs, using the same welding process, within the
limits of the essential variables of QW-350.
QW-401.1 Essential Variable (Procedure). A change in a welding
condition which will affect the mechanical properties (other than notch
toughness) of the weldment (e.g., change in P-Number, welding process, filler
metal, electrode, preheat or postweld heat treatment).
QW-401.2 Essential Variable (Performance). A change in a welding
condition which will affect the ability of a welder to deposit sound weld metal
(such as a change in welding process, deletion of backing, electrode, F-Number,
technique, etc.).
QW-401.3 Supplementary Essential Variable (Procedure).
A change in a welding condition which will affect the
notch-toughness properties of a weldment (for example, change in welding
process, uphill or down vertical welding, heat input, preheat or PWHT, etc.).
Supplementary essential variables are in addition to the essential variables
for each welding process.
QW-401.4 Nonessential Variable (Procedure). A change in a welding
condition which will not affect the mechanical properties of a weldment (such
as joint design, method of back gouging or cleaning, etc.)
NOTES: (1) Positions of welding as shown in QW-461.1 and
QW-461.2. F-Flat H – Horizontal V – Vertical O- Overhead
(2) Pipe 27⁄8 in. (73 mm) O.D. and over.(3) See diameter
restrictions in QW-452.3, QW-452.4, and QW-452.6.
Legend: _ Change t Thickness
+ Addition ↑Uphill − Deletion ↓Downhill
Base metal defects in
weld bevel for Pipes and Fittings for Joint Fitup – to be corrected if
permissible as per ASME Sec II A, ASME B31.3, SAES-W-011 and other applciable
specifications.
328.4.3 Alignment
(b) Circumferential Welds
(1) If component ends are trimmed as shown in Fig.
328.3.2 sketch (a) or (b) to fit backing rings or consumable
inserts, or as shown in Fig. 328.4.3 sketch (a) or (b) to
correct internal misalignment, such trimming shall not reduce the finished wall
thickness below the required minimum wall thickness, tm.
(2) Component ends may be bored to allow for a completely
recessed backing ring, provided the remaining net thickness of the finished
ends is not less than tm.
(3) It is permissible to size pipe ends of the same
nominal size to improve alignment if wall thickness requirements are maintained.
(4) Where necessary, weld metal may be deposited inside
or outside of the component to permit alignment or provide for machining to
ensure satisfactory seating of rings or inserts.
(5) When a girth or miter groove weld joins components of
unequal wall thickness and one is more than 11⁄2 times the thickness of the
other, end preparation and geometry shall be in accordance with acceptable
designs for unequal wall thickness in ASME B16.25.
(6) Buttweld fittings manufactured in accordance with ASME
B16.9may be trimmed to produce an angular joint offset in their connections to
pipe or to other buttweld fittings without being subject to design
qualifications in accordance with para. 304.7.2 provided the total
angular offset produced between the two jointed parts
does not exceed 3 deg.
328.4.3 Alignment
(a) Circumferential
Welds (1) Inside surfaces of components at
ends to be joined in girth or miter groove welds shall be aligned
within the
dimensional limits in the WPS and the engineering design.
(2) If the external surfaces of the components are not
aligned, the weld shall be tapered between them.
SAES-W-011
11.3.5 Buttering or weld build-up
on joints
11.3.5.1 Buttering or weld
build-up on the prepared surfaces shall not exceed the lesser of ⅓ of the base metal thickness or 10 mm without the
approval of CSD. If the buttering or build-up exceeds this, then the following
requirements shall apply:
a) The buttering operation shall
be witnessed by Saudi Aramco Inspection.
b) The buttering shall be inspected by RT, and PT or MT after
completion of the build-up but before final welding of the joint.
18.6 Damage or deformation to the base metal or welds,
including dimensional changes, caused by external forces (intentional or
accidental) requires special repair and inspection procedures to be submitted
to Saudi Aramco Inspection and if necessary forwarded to CSD for review and
approval prior to undertaking the repairs.
11.14.5 The back purge for stainless steel and nickel alloys
shall reduce the oxygen level below 0.05%. An oxygen analyzer should be used to
determine the oxygen content inside the pipe during purging. If more than 20
joints are to be welded at the same time then minimum of 10% of the total
joints shall be analyzed.
11.16 Weld encroachment and
minimum distance between welds.
The distances shall be measured between the edges of the
adjacent cap passes. These restrictions do not apply if one of the welds has
been post weld heat treated prior to making the second weld or both welds have
been post weld heat treated and inspected.
11.16.1 The minimum distance
between parallel butt welds shall be 20 mm or three times the wall thickness of
the joint, whichever is greater.
11.16.2 Pressure containing welds (e.g., nozzles and other
attachments) shall be separated from other pressure containing welds by no less
than 20 mm or three times the joint thickness, whichever is greater.
Radiography of the butt welds is required for situations in which the minimum
separation is not achieved. For joints other than butt welds, other appropriate
inspection methods shall be used, depending on the geometry and material.
11.8 If any grinding reduces the base metal thickness to less
than the design minimum, the ground area shall be rewelded and ground flush
with the original base metal surface or the component shall be replaced.
Rewelding shall be done only with the prior approval of Saudi Aramco
Inspection.
Production hardness testing for welds in P-No 1 material in
sour or PWHTed service shall also be performed. 10% of the welds shall be
sampled. The maximum allowed hardness is 200 BHN.
Friday 24 August 2012
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welding inspector jobs
Job Details
- Area of WorkService / Installation / Repair, Maintenance
- IndustryOil & Gas / Petroleum
- LocationQatar
- Experience3 - 6 Yrs
Job Description
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