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Sunday, April 11, 2010

Re: [MW:4784] Testing of Materials

Dear Rathinaval,
 
Depending the classification requirements, he may ask for longitudinal tensile tests. I added a copy of some part of the rules for materials and welding of Bureau Veritas to this E-mail. In case you use none approved  filler material he may request a longitudinal test.
You can find these rules on www.veristar.com under erules.
 
best regards,
 
Dick Overkleeft
 
Article 2 Welding procedure qualification tests for C and C-Mn steels for ship hull and other welded structures in general  




2.1 Plates butt weld with full penetration  


2.1.1  Assembly of test pieces

Preparation and welding are to be in accordance with the pWPS and under the general condition of production welding which it represents.



If tack welds and / or start and stop points are a condition of the weld process they are to be fused into the joint and are to be included in the test pieces.

The test assembly is to be of a size sufficient to ensure a reasonable heat distribution and is to have the minimum following dimensions (see Fig 1):

  • manual or semiautomatic welding:
    length L=6t, min. 350mm;
    width W with W/2=3t, min. 150mm.
  • automatic welding:
    length L=min.1000 mm;
    width W with W/2=4t, min. 200 mm.

In the case of steel plates impact tested in the longitudinal direction (CVN-L), the butt weld of the test piece is perpendicular to the rolling direction of the two plates.

In the case of steel plates impact tested in the transversal direction (CVN-T), the butt weld of the test piece is parallel to the rolling direction of the two plates.



Figure 1   - Test assembly for plate butt weld
Test assembly for plate butt weld



2.1.2  Examinations and tests

Non-destructive examinations and destructive tests required according to  Tab 1 are to be carried out, while the location of the test specimens is to be in accordance with Fig 2.





Figure 2 - Location of test specimens


2.1.3  Non-destructive examinations

Non-destructive examinations are to be carried out after any required or specified post-weld heat treatment and prior to the cutting of test specimens.



Imperfections detected by visual or non-destructive testing shall be assessed in accordance with ISO 5817 class B, except for the following imperfections for which the level C applies:

  • excess weld metal or convexity,
  • excess throat thickness, and
  • excess of penetration.

Table 1 - Examinations and tests

Type of examination or test
Extent of examination or test
( 1 )  

Dye penetrant according to ISO 3452 (or equivalent accepted standard) or magnetic particle testing; for non-magnetic materials, dye penetrant only.



( 2 )  

For t ≥ 12mm, the face and root bends are preferably to be replaced by 4 side bends.



( 3 )  

3 sets each of 3 specimens as per [2.1.7].



( 4 )  

Only required for high strength steels with minimum specified yield strength equal to or greater than 355N/mm2.



( 5 )  

Required only when the use of non-approved filler metal has been accepted (see [1.2.3]).



Visual examination

100%

Surface crack detection (1)

100%

Radiographic or ultrasonic examination

100%

Transverse tensile test

2 specimens

Transverse bend tests (2)

2 root and 2 face specimens

Charpy V-notch impact tests (3)

3 sets

Macro examination

on 1 section

Hardness test (4)

on 1 section

Longitudinal tensile test (5)

1 specimen

2.1.4  Transverse tensile tests

Specimens for transverse tensile tests are to be in accordance with Ch 1, Sec 2, [2.1.11].



The tensile strength recorded for each specimen is to be not less than the minimum required for the parent metal; the location of the fracture is to be reported.

When butt welds are made between plates of different grades, the tensile strength to be obtained on the welded assembly is to be in accordance with the requirement of the grade having lower strength.

2.1.5  Tensile tests on cylindrical specimens

When required (see  Tab 1), a round tensile specimen is to be cut along the weld axis to the dimension given in Ch 1, Sec 2, Fig 3, in the all weld metal.



Where the size of the deposited metal is too small, a 6 mm diameter specimen may be taken or a deposited weld metal test is to be carried out in accordance with the requirements of Sec 2.

The tensile properties recorded (yield stress ReH, tensile strength Rm and elongation A5) are to be not less than the minimum required for the approval of the appropriate grade of consumables.

When more than one welding process or type of consumable has been used to make the test weld, test specimens are to be removed from the area of the weld where each was used with the exception of those processes or consumables used to make the first weld run or root deposit.

2.1.6  Bend tests

Transverse root bend, face bend and side bend specimens are to be machined to the dimensions given in Ch 1, Sec 2, [3.1].



For dissimilar or heterogeneous butt-joints, one longitudinal bend test may be used instead of transverse bend tests.

The test specimens are to be bent on a mandrel having a diameter equal to 4 times the thickness of the specimen; the bending angle is to be 180˚.

After testing, the test specimens are not to reveal any open defect, in any direction, greater than 3 mm. Defects appearing at the corners of the test specimen during testing are to be investigated case-by-case.

When butt welds are made between plates of different grades, face and root longitudinal bend test specimens may be used instead of the transverse bend test specimens.

2.1.7  Impact tests

Dimensions and testing of Charpy V-notch impact test specimens are to be in accordance with Ch 1, Sec 2.



Charpy V-notch impact test specimens in accordance with Ch 1, Sec 2 are to be sampled from 1 to 2 mm below the surface of the parent material, transverse to the weld and on the side containing the last run.

The Charpy V-notch specimens are located in the butt-welded joint as indicated in Fig 3 and Fig 4, and the V-notch is to be cut perpendicular to the surface of the weld.



Figure 3   - Location of V-notch for normal heat input ≤ 50 kJ/cm
Location of V-notch fornormal heat input ≤ 50 kJ/cm
a : 
Centre of weld "WM"
b : 
On fusion line "FL"
c : 
In HAZ, 2 mm from fusion line
* : 
For one side pass welding over 20 mm "WM" FL and HAZ, 2mm from fusion line to be added on root side.



The test temperature and absorbed energy are to be in accordance with  Tab 2.

When butt welds are made between different steel grades / types, the test specimens are to be taken from the side of the joint with steel of lower toughness level. Temperature and absorbed energy results are to be in accordance with the minimum value required for the steel of lower toughness level.

Where more than one welding process or consumable has been used to make the test weld, impact test specimens are to be removed from the respective areas where each was employed. This should not apply to the process or consumables used solely to make the first weld run or root deposit.

When cast or forged material with specified impact values is to be welded, test temperature and absorbed energy are to be in accordance with the requirements of the base material.



Figure 4 - Location of V-notch for high heat input > 50 kJ/cm



2008/10 edition (entry into force 2009/01/01)
Table 2 - Impact test requirements for butt joints (t ≤ 50 mm)

2008/10 edition (entry into force 2009/01/01)

Unless otherwise agreed with the Society, the test temperature and absorbed energy of steels not covered by these requirements are to be in accordance with the specification of the parent metal.

2.1.8  Macro examinations

The test specimens are to be prepared and etched on one side to clearly reveal the weld metal, fusion line, the heat affected zone (HAZ) and about 10mm of unaffected parent metal.



The examination shall reveal a regular weld profile, through fusion between adjacent layers of weld and base metal and the absence of defects such as cracks, lack of fusion etc.

2.1.9  Hardness tests

Hardness testing is required for steels with minimum specified yield strength equal to or greater than 355N/mm2. Unless otherwise agreed, the Vickers method HV10 is to be used.



The indentations are to be made in the weld, heat affected zones, and the parent metals measuring and recording the hardness values. Two rows of indentations are to be carried out in accordance with Fig 5.

For each row of indentations, there is to be a minimum of 3 individual indentations in the weld, the heat affected zones (both sides) and the parent metals (both sides).

The distance between the indentations may vary from 0,5 to 2 mm depending on the zone tested.

Typical example of hardness indentations are given in Fig 5.



Figure 5   - Examples of hardness indentations
Examples of hardness indentations



The results of hardness tests are not to exceed 350 HV for steels with a specified minimum yield strength less than or equal to 420N/mm2.



2.2 Plates fillet weld  


2.2.1  Assembly and welding

Preparation and welding are to be in accordance with the pWPS and under the general condition of production welding which it represents.



If tack welds are a condition of the weld process they are to be fused into the joint and are to be included in the test pieces.

The test assembly is welded on one side only. For single pass manual and semi-automatic welding, a stop/restart is to be included in the test length and its position is to be clearly marked for subsequent examination.

The test assembly is to be of a size sufficient to ensure a reasonable heat distribution and is to have the minimum following dimensions (see Fig 6):

  • manual or semiautomatic welding:
    length L=6t, min. 350mm;
    width W=3t, min. 150mm.
  • automatic welding:
    length L=min.1000 mm;
    width W=3t, min. 150 mm.
2.2.2  Examinations and tests

Non-destructive examinations and destructive tests required according to  Tab 3; a discard of 50 mm from both edges is permitted.





Figure 6   - T fillet joint on plates
T fillet joint on plates




Table 3 - Examinations and tests

2.2.3  Visual examination and surface crack detection

Non-destructive examinations are to be carried out after any required or specified post-weld heat treatment and prior to the cutting of test specimens.



Imperfections detected are to be assessed in accordance with [2.1.3].

2.2.4  Macro examination

The test specimen is to be prepared and etched on one side to clearly reveal the weld metal, fusion line, root penetration, the heat affected zone and about 10mm of unaffected base material.



The examination shall reveal a regular weld profile, through fusion between adjacent layers of weld and base metal and the absence of defects such as cracks, lack of fusion etc.

The dimensions of leg size, throat and penetration are to be reported.

2.2.5  Fracture test

The fracture test is to be performed by folding the upright plate onto the through plate. Evaluation is to be concentrated on cracks, porosity and pores, inclusions, lack of fusion and incomplete penetration. Imperfections that are detected shall be assessed in accordance with ISO 5817 Class B.



2.2.6  Hardness test

Hardness testing is required for steels with minimum specified yield strength equal to or greater than 355N/mm2. Unless otherwise agreed, the Vickers method HV10 is to be used.



The indentations are to be made in the weld, heat affected zones, and the parent metals measuring and recording the hardness values. Two rows of indentations are to be carried out in accordance with Fig 7.



Figure 7   - Macro and hardness indentations
Macro and hardness indentations



For each row of indentations, there is to be a minimum of 3 individual indentations in the weld, the heat affected zones (both sides) and the parent metals (both sides).

The results of hardness tests are not to exceed 350 HV for steels with a specified minimum yield strength less than or equal to 420N/mm2.



2.3 Pipes butt weld with full penetration  


2.3.1  Assembly and welding

Preparation and welding are to be in accordance with the pWPS and under the general condition of production welding which it represents.



If tack welds are a condition of the weld process they are to be fused into the joint and are to be included in the test pieces.

The test assembly is to be in accordance with Fig 8.



Figure 8   - Pipe weld test assembly
Pipe weld test assembly

W : minimum value = 150 mm; D = outside diameter




2.3.2  Examinations and tests

Non-destructive examinations and destructive tests required according to  Tab 1. The location of the test specimens is to be in accordance with Fig 9.





Figure 9


2.3.3  Results

The results are to comply with the requirements for plate buttt weld in [2.1].





2.4 Re-testing 


2.4.1 

If the test piece fails to comply with any of the requirements for visual or non-destructive testing, one further test piece is to be welded and subjected to the same examination.



If this additional test piece does not comply with the relevant requirements, the pWPS is to be regarded as not capable of complying with the requirements without modification.

2.4.2 

If any test specimens fails to comply with the relevant requirements for destructive testing due to weld imperfection only, two further test specimens shall be obtained for each one that failed. These specimens can be taken from the same test piece if there is sufficient material available or from a new test piece, and is to be subjected to the same test. If either of these additional test specimens does not comply with the relevant requirements, the pWPS is to be regarded as not capable of complying with the requirements without modification.



2.4.3 

If a tensile test specimen fails to meet the requirements, the re-testing is to be in accordance with  Ch 1, Sec 2, [2.3].



2.4.4 

If there is a single hardness value above the maximum values allowed, additional hardness tests shall be carried out (on the reverse of the specimen or after sufficient grinding of the tested surface). None of the additional hardness values is to exceed the maximum hardness values required.



2.4.5 

The re-testing of Charpy V-notch impact test specimens are to be carried out in accordance with  Ch 1, Sec 2, [4.4].



2.4.6 

Where there is not sufficient material remaining in the test piece to provide the additional test specimens, a further assembly shall be welded using the same procedure to provide the additional specimens.





2.5 Range of approval 


2.5.1  General

The approval of a WPS obtained by a yard or Manufacturer is valid for welding in workshops under the same technical and quality management, to the Society's satisfaction.



The welding procedure is to be used within the range of the parameters indicated below; changes outside the range specified of one or more of these parameters require a new qualification test.

2008/10 edition (entry into force 2009/01/01)
2.5.2  Parent metal

For hull structural steel grades A to FH40 as defined in  Ch 2, Sec 1, [2], the following applies :



  • For each strength level, welding procedures are considered applicable to the same and lower toughness grades as that tested;
  • For each toughness grade, welding procedures are considered applicable to the same and two lower strength levels as that tested;
  • For applying the above a) and b) to high heat input processes above 50kJ/cm, e.g. the two-run technique with either submerged arc or gas shielded metal arc welding, electroslag and electrogas welding, welding procedure is applicable that toughness grade tested and one strength level below.

Where steels used for construction are supplied from different delivery conditions from those tested, the Society may require additional tests.

For weldable C and C-Mn hull steel forgings as defined in  Ch 2, Sec 3, [2], the following applies :

  • Welding procedures are considered applicable to the same and lower strength level as that tested;
  • Qualification tests on quenched and tempered hull structural steel forgings do not qualify other delivery condition and vice-versa.

For weldable C and C-Mn hull steel castings as defined in  Ch 2, Sec 4, [2], the following applies:

  • Welding procedures are considered applicable to the same and lower strength level as that tested;
  • Qualification tests on quenched and tempered hull structural steel castings do not qualify other delivery condition and vice-versa.
2008/10 edition (entry into force 2009/01/01)
2.5.3  Thickness

The qualification of a WPS carried out on a welded assembly of thickness t is valid for the thickness range given in  Tab 4 .



In addition to the requirements of  Tab 4, the range of approval for fillet welds shall be as follows ;

  • Single pass fillet welds; for throat thickness "a" the range of approval is "0,75 a" to "1,5 a".
  • Multipass fillet welds; for throat thickness "a" the range of approval is as for multipass butt welds (i.e. a=t).

For the vertical-down welding, the test piece thickness t is always taken as the upper limit of the range of application.

For unequal plate thickness of butt welds the lesser thickness is the ruling dimension.

Notwithstanding the above, the approval of maximum base material thickness for any technique is restricted to the test assembly thickness if three of the hardness values in the heat affected zone are found to be within 25 HV of the maximum permitted, as stated in  [2.1.9] and  [2.2.6].


Table 4 - Approved thickness range

2.5.4  Pipe diameter

Qualification tests on an assembly of pipes of diameter D is valid for diameters in the range given in  Tab 5.




Table 5 - Approved diameter range

2.5.5  Welding position

Standard positions are given in Fig 10 for plates and pipes.



Approval for a test made in any position is restricted to that position.

To qualify all positions, test assemblies are to be welded for highest and lowest heat input position and all applicable tests are to be made on those assemblies.

For plates butt welds with full penetration, the highest heat input position is normally the vertical upwards position and the lowest heat input position is normally the horizontal-vertical position.

2.5.6  Welding process

The approval is only valid for the welding process(es) used in the qualification tests. It is not permitted to change from a multi-run to a single run.



For multi-process procedures the welding procedure approval may be carried out with separate qualification tests for each welding process. It is also accepted to make the qualification test as a multi-process procedure test. The approval of such a test is only valid for the process sequence carried out during the multi-process procedure test.

For the manual metal arc welding process (111) and semi-automatic welding process with flux cored wire without shielding gas (114), the approval obtained is valid for the diameter of the electrode used in the welding procedure test plus or minus one electrode diameter size for each run, except for the root run of the one side welded assembly without backing strip, for which no size change is allowed.

For the gas metal arc welding processes (131, 135, 136), the approval obtained for face and/or back shielding gas is restricted to the type of gas (nominal composition) used during the procedure test. The approval is restricted to the wire system used in the approval test (e.g. single wire or multi-wire) and, in the case of automatic welding, to the relevant welding technique.

For the submerged arc processes (12), the approval obtained is restricted to the wire system used in the approval test (e.g. single wire or multi-wire) and relevant welding technique (T, M, U). Change in the flux trade mark requires new welding procedure approval tests.


2008/10 edition (entry into force 2009/01/01)

Figure 10 - Welding positions according to ISO Standard


2008/10 edition (entry into force 2009/01/01)
2.5.7  Welding consumables

Except high heat input process (over 50KJ/cm), welding consumables tested cover other approved welding consumables having the same grade mark including all suffixes specified in  Sec 2 with that tested.



Change in the trade name of filler metal requires new welding procedure approval tests when Charpy V-notch impact tests are required at temperature strictly below -20˚C.

2.5.8  Heat input

The upper limit of heat input approved is 25% greater than that used in welding the test piece or 50KJ/cm whichever is smaller, except that the upper limit is 10% greater than that for high heat input processes over 50KJ/cm.



The lower limit of heat input approved is 25% lower than that used in welding the test piece.

2.5.9  Preheat and interpass temperature

The minimum preheat temperature is not to be less than that used in the qualification test.



The minimum interpass temperature is not to be less than the specified preheat temperature.

The maximum interpass temperature is not to be higher than that used in the qualification test.

2.5.10  Post-weld heat treatment

The heat treatment used in the qualification test is to be maintained during manufacture. Holding time may be adjusted as a function of thickness.



2.5.11  Type of joint

The range of approval depending on type of welded joint for test assembly is given in  Tab 6.



New qualification tests may be required by the Surveyor when changes occur in the geometry of the bevel which may significantly affect the penetration or fusion.

page contains added or updated content


2010/4/8 Rathinavel Arumugam <rathinavel1976@gmail.com>
Dear All !
 
I have one job for marine classification. Material is AISI 4140 and dia id 355.  Our Surveyor is insisting for Longitudinal Tensile Test  and  it cause huge material wastage. Is it approved to go with Transverse direction Test piece for Tensile Test and if so what is the acceptance critiria?
 
Please Clarify!
 
A.Rathinavel
[ QA/QC MANAGER / CSWIP 3.1 ]

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