GB/T 30583-2014 English PDF (GB/T30583-2014)

GB/T 30583-2014: Specification for post weld heat treatment of pressure equipment
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GB/T 30583-2014
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 25.200
J 36
Specification for post weld heat treatment of pressure
equipment
ISSUED ON: MAY 06, 2014
IMPLEMENTED ON: DECEMBER 01, 2014
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration of the People's Republic of China.
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Normative references ... 4 
3 Terms and definitions... 4 
4 Basic process ... 5 
5 Equipment, instruments, temperature measuring supplies and thermal insulation
materials ... 13 
6 Technical preparation ... 15 
7 Heating, temperature control ... 17 
8 Temperature measurement ... 18 
9 Heat insulation ... 20 
10 Post weld heat treatment report ... 21 
Annex A (informative) Diagram of post weld heat treatment thickness (δPWHT) ... 22 
Annex B (informative) Recommended width of heated band and gradient control band
for partial post weld heat treatment of cylinders ... 31 
Annex C (normative) Determination method of effective heating area of post weld heat
treatment furnace ... 32 
Annex D (informative) Record table of overall post weld heat treatment outside the
furnace of pressure equipment (examples) ... 35 
Specification for post weld heat treatment of pressure
equipment
1 Scope
This document specifies general basic technical requirements for post weld heat
treatment of steel pressure equipment.
This document applies to post weld heat treatment of boilers and pressure vessels
(excluding gas cylinders).
2 Normative references
The following referenced documents are indispensable for the application of this
document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
GB/T 3375, Welding terminology
GB/T 9452, Testing method for working zone of heat treatment furnace
NB/T 47014, Welding procedure qualification for pressure equipment
3 Terms and definitions
For the purposes of this document, the terms and definitions defined in GB/T 3375,
GB/T 9452 as well as the followings apply.
3.1 weldment
Welded pressure equipment or parts thereof.
3.2 post weld heat treatment
The process that, to eliminate the welding residual stress and improve the structure and
performance of the welded joint, the weldment is uniformly heated to a sufficiently high
temperature below the phase transition point of the metal, kept for a certain period of
time, and then uniformly cooled.
3.3 soak band
During partial post weld heat treatment, the area that the volume range over which the
weldment reaches the specified temperature is on its surface. The soak band includes
the weld zone, fusion zone, heat-affected zone and its adjacent base metal.
3.4 heated band
The area that during partial post weld heat treatment, heating is carried out to ensure
that the weldment obtains the specified volume range of temperature uniformity.
3.5 gradient control band
The area that during partial post weld heat treatment, to prevent heat dissipation in the
temperature range and heating range of the weldment, a thermal insulation material is
laid on its surface.
3.6 holding temperature
To achieve the purpose of post weld heat treatment, the indicated volume range of the
weldment or its partial soak band shall be maintained within the specified temperature
range within the necessary time.
3.7 holding time
The time during which the indicated volume range of the weldment or its local soak
band is maintained at the holding temperature. The holding time is calculated from the
time when the temperature of all temperature measuring points reaches the minimum
holding temperature. It ends when the temperature of any one of the temperature
measuring points is lower than the minimum holding temperature.
4 Basic process
4.1 General provisions
4.1.1 In addition to complying with this Standard, the post weld heat treatment of
pressure equipment shall also comply with the requirements of product standards,
design documents and contracts.
4.1.2 In addition to this Standard, the effective results that have been proved through
experimental research and/or practice, after they are approved by relevant parties and
included in corporate standards, can also be used for post weld heat treatment of
pressure equipment in this organization.
4.1.3 The thermal effects of carbon steel and low alloy steel weldments below 490°C,
and the thermal effects of high alloy steel weldments below 315°C, are not treated as
post weld heat treatment.
4.1.4 The constructer of pressure equipment shall have technical personnel, who have
certain professional knowledge and sufficient practical experience, after they master
the following basic conditions, prepare "Process specifications for post weld heat
treatment" for each (piece) weldment:
a) Welding properties of steel and welding consumables for weldments. Adaptability
to post weld heat treatment;
b) Actual tempering temperature of steel. Post weld heat treatment conditions for test
piece of welding material mechanical properties;
c) Weldment design document specification, service requirements and construction
process;
d) Post weld heat treatment environment, post weld heat treatment methods,
equipment, device characteristics and procedures.
4.1.5 The welding process evaluation items used for weldments shall include all
important factors and supplementary factors that may occur during the implementation
of the "Process specifications for post weld heat treatment".
4.1.6 Post weld heat treatment operators should be trained and assessed before they can
take up their posts. They shall be familiar with and master the "Process specifications
for post weld heat treatment" for weldments.
4.1.7 The product welding test piece shall be prepared by the actual welding process
(including post weld heat treatment) that makes lower mechanical properties.
4.2 Post weld heat treatment thickness δPWHT
4.2.1 The δPWHT of equal thickness full penetration butt joint is the weld thickness
(excess height is not counted). At this time, δPWHT is the same as the base metal
thickness.
4.2.2 In butt weld joints, δPWHT is equal to the thickness of the butt weld. In welded
joints connected by fillet welds, δPWHT is equal to the fillet weld thickness. In welded
joints connected by composite welds, δPWHT is equal to the greater of the thickness of
butt weld and fillet weld.
4.2.3 The δPWHT for stud welding is equal to the nominal diameter of the stud.
4.2.4 The values of δPWHT when welding pressure components with different
thicknesses are as follows (see Annex A):
a) Among the two adjacent pairs of pressure-receiving elements, take the thickness
of the base metal on the thinner side;
b) For the head structure inside the cylinder, take the larger of the thickness of the
cylinder wall and the thickness of the fillet weld;
c) When the tube sheets, flat heads, covers, flanges or flanges are welded to the barrel,
except for the case that the flange thickness δf is taken when δf >δo shown in Figure
A.3 in Annex A, take the cylinder wall thickness for the rest;
d) When connecting parts such as nozzles and manholes are welded to the cylinder
body and head, take the larger of the thickness of the neck weld of the connecting
piece, the thickness of the barrel weld, the thickness of the head weld, or the
thickness of the fillet weld of the connecting piece such as the reinforcing plate;
e) When the nozzle is welded to the flange, take the thickness of the weld at the joint
of the nozzle;
f) When the non-pressure components are welded with the pressure parts, take the
thickness of the weld at the welding point;
g) When the pipe and the tube sheet are welded, take the thickness of the weld;
h) When welding and repairing, take the thickness of the weld metal filled.
4.2.5 Thickness of post weld heat treatment calculation holding time:
a) When the overall post weld heat treatment is carried out, the maximum δPWHT of
the part without post weld heat treatment shall be used;
b) When multiple (pieces) pressure equipment or parts are installed in the same
furnace, the maximum δPWHT on the weldment without post weld heat treatment
shall be used.
4.3 Post weld heat treatment methods
4.3.1 Overall post weld heat treatment
The overall post weld heat treatment has the following two forms. When conditions
permit, the overall heating method in the furnace shall be used:
a) Load the weldment into a closed furnace for overall heating;
b) Conduct overall heating inside or outside the weldment.
4.3.2 Segmental post weld heat treatment
When the overall weldment is heated in segments, the length of the overlapping portion
of each heated segment is at least 1500mm. Heat insulation measures shall be taken for
weldments (including their pipe joints) of non-heating parts. Prevent harmful
temperature gradients.
4.3.3 Partial post weld heat treatment
4.3.3.1 Figure 1 shows the average temperature, heating and thermal insulation range
shall not exceed (δ is the maximum thickness of the weldment shell, in
mm). It shall not exceed 220°C/h;
c) During the heating period of the weldment, the temperature difference within the
range of any length of 4600mm within the heating range shall not be greater than
140°C;
d) During the heat holding period of the weldment, the difference between the
highest and lowest temperature within the heating range shall not be greater than
80°C;
e) During the heating and holding period, the atmosphere within the heating range
shall be controlled. Prevent excessive oxidation of the weldment surface;
f) When the temperature of the weldment is higher than 400°C, the cooling rate
within the heating range shall not exceed (δ is the maximum thickness
of the weldment shell, in mm). It shall not exceed 280℃/h;
g) During the heating and cooling process of the weldment above 400℃, the heating
and cooling rate shall not be less than 55℃/h. If there is no harmful effect, the
heating and cooling speed can be reduced;
h) When the weldment is released, the weldment shall not be higher than 400℃.
Once out of the oven it shall be cooled in still air.
4.4.10 General limits for out-of-furnace post weld heat treatment process parameters:
a) The post weld heat treatment process outside the furnace is the same as the post
weld heat treatment process in the furnace;
b) When the heating area is cooled, the temperature in the range shown in the soak
band is lower than 400℃. And then it can be cooled in still air.
5 Equipment, instruments, temperature measuring supplies
and thermal insulation materials
5.1 The post weld heat treatment furnace shall meet the following requirements:
a) Do not use coal or coke as fuel;
b) Use automatic methods such as program controller or computer to control the post
weld heat treatment process. The temperature in the furnace and the temperature
rise (fall) speed range can be adjusted;
c) The medium used to heat the weldment in the furnace can flow sufficiently;
d) During the heat treatment process, the furnace shall maintain positive pressure in
a timely manner;
e) The atmosphere in the heating area of the furnace can be controlled. Prevent
excessive oxidation of the weldment surface;
f) It shall be equipped with temperature measurement, temperature control and alarm
system. The temperature can be automatically recorded;
g) At least the following technical requirements shall be specified:
1) Rated load capacity;
2) Size of the loading space in the furnace;
3) Loading regulations into the furnace;
4) Maximum heating rate at rated load;
5) Maximum cooling rate at rated load;
6) Accuracy level of temperature control instrument;
7) Accuracy level of temperature measuring instrument;
h) There shall be product manuals and operation manuals.
5.2 The effective heating area of the post weld heat treatment furnace shall be
determined according to the provisions of Annex C. The schematic diagram of the
effective heating area shall be placed in a prominent position of the heat treatment
furnace. The furnace temperature uniformity of the effective heating area of the post
weld heat treatment furnace is generally ±10℃, ±15℃, ±20℃.
5.3 Insulation materials, temperature control instruments and temperature measuring
instruments shall meet corresponding standards. The product shall have quality
certificate and instruction manual.
5.4 Manufacturers of thermocouples and compensation wires shall have corresponding
qualifications. The used thermocouple and compensation wire shall have quality
certificate.
5.5 All kinds of measuring instruments shall pass the measurement inspection according
to the standard. Before use, calibrate as specified.
5.6 The post weld heat treatment heating, temperature control, temperature
measurement device and the whole system outside the furnace shall be inspected and
treatment.
6.2 For the specification for post weld heat treatment process of the overall post weld
heat treatment outside the furnace (including the overall post weld heat treatment
outside the furnace), an expert review shall be organized if necessary. The main contents
of the specification for post weld heat treatment process include:
a) Requirements specified in the standards, contracts and design documents on
which they are based;
b) Basic condition of weldment: name, number, designation, structure, size, material,
thickness and quality;
c) Thermal calculation of post weld heat treatment of weldment as a whole and each
part;
d) Weldment thermal deformation prevention and control measures;
e) Post weld heat treatment heating method, heater name, model, specification,
quantity and placement;
f) Auxiliary devices (such as diversion umbrellas) and installation for post weld heat
treatment;
g) Post weld heat treatment parameters: post weld heat treatment thickness δPWHT,
...