Welds hardness tests

Hardness testing shall be conducted for welding and brazing procedure qualification tests, hot and cold bent formed piping, pipe components, production weldments, and brazements. 

Other hardness testing methods for welding procedure qualification may be allowed when permitted by engineering design. 

Non-PWHT (as-welded condition) hardness testing shall be conducted of the following ... 

Production weldments that do not meet the hardness test requirements (hard welds) shall be removed and replaced. The use of additional heat treatment that may correct the hardness of the weldment requires a supporting WPS/PQR with approval of the engineering design. 

This decay rate is nearly equivalent to that exhibited by one g of radium in equilibrium with its disintegration products. A miUicurie (mCi) is 0.001 curie, curie point See magnetized curie point, curing See autoclave nitrogen atmosphere cure extruder wire and cable process, dry cure inhibitor prepreg volatile content reinforced plastic resin transfer molding test, Barcol hardness test, scorch Mooney thermoset plastic vulcanization welding, induction. 

Non-destructive test (1) A test that yields information about failure under mechanical stress without actually stressing to failure. (2) More broadly, any test to evaluate a property of a material, part, or structure that does not significantly damage the part. Techniques used include ultrasound, magnetic inspection of metals and welds. X-ray inspection, infrared, nuclear magnetic resonance, and sonic analysis. Although an indentation-hardness test leaves a permanent mark, in many tests of parts it is nondestructive. 

Hardness testing is a critical NDE tool utilized to ensure that the welding, heat treatment and fabrication methods... 

Weld procedures require hardness testing on a section of the weld. The tests are performed on the weld metal, the HAZ and the base metal. Production tests are on the weld metal only for each welding process, filler metal and technique used. The location for the testing of the production welds shall be at the discretion of the inspector. 

One set of hardness tests shall be taken in the weld metal and one in die HAZ. Each set shall consist of three samples. 

Note Spot welding characteristics were investigated by hardness testing a cross section of the weld nugget. The hardness survey indicated that decomposition takes place after short-term thermal exposure at 315 (600 °F). Increase in hardness is confined to the weld metal (a)... 

Hardness testing should be conducted on the base metal, weld metal, and heat affected zone, as follows ... 

Hardness tests of production welds and of hot-bent and hot-formed piping are intended to verify satisfactory heat treatment. The hardness limit applies to the weld and to the heat-affected zone (HAZ) tested as close as practicable to the edge of the weld ... 

There is hardly a metal that cannot, or has not, been joined by some welding process. From a practical standpoint, however, the range of alloy systems that may be welded is more restricted. The term weldability specifies the capacity of a metal, or combination of metals, to be welded under fabrication conditions into a suitable stmcture that provides satisfactory service. It is not a precisely defined concept, but encompasses a range of conditions, eg, base- and filler-metal combinations, type of process, procedures, surface conditions, and joint geometries of the base metals (12). A number of tests have been developed to measure weldabiHty. These tests generally are intended to determine the susceptibiHty of welds to cracking. 

Aluminium coatings exposed as sprayed show remarkable protective properties and in many cases the only evidence of age is the appearance of small hard nodules of aluminium oxide, and these do not appear to be deleterious. However, the dead white of the sprayed surface soon becomes discoloured by dirt and so a paint covering is usual. A chromate inhibitor is not essential and two coats of a simple vinyl-based sealing paint have given remarkable results in the tests of the American Welding Society over periods of 12 and 15 years. 

When specified, the hardness of parts, welds, and heat-affected zones shall be verified as being within the allowable values by testing. The method, extent, documentation, and witnessing of the testing shall be mutually agreed upon by the purchaser and the vendor. 

From this test, antiwear and extreme-pressure data were determined, such as welding load, load wear index and wear scar diameter under a load of 40 decanewtons (daN), 60 daN and 80 daN, respectively. First, evaluations were performed on the three original nonmodified hard-core RMs, then evaluations were performed on the sulfur-functionalized ones. Four-ball test data (results only for one concentration 10 wt% additive) are summarized in Table 3.9 (Delfort et al., 1995 and 1999) for ... 

Modified hard-core RMs by phosphosulfurized compound. Improved extreme-pressure and antiwear properties have also been obtained with the introduction of some chemical species, such as sulfur, phosphorus or boron derivatives, into the colloidal core (Delfort et al., 1998 Inoue, 1993 Inoue and Nose, 1987). Welding loads, load wear index and wear scar diameter at 5 wt% of a CaC03 core surrounded by a calcium alkylaryl-sulfonate surfactant shell, and modified by phosphosulfurized calcium carbonate core were evaluated for calcium dialkyl dithiophosphate (CaDTP) and calcium trithiophosphate (CaTTP) with the four-ball extreme-pressure test (ASTM D2783 standard method). Both modified products exhibit improved extreme-pressure performances (welding load and load wear index), while their antiwear properties (wear scar diameter) compared to those of the original micellar substrate remain at least at the same level. 

The manufacturer shall perform all fabrication and welding in accordance with an established written procedure. The first production pipe shall be sectioned and tested. Included in the testing shall be the normal physical property and nondestructive testing as well as a microhardness traverse across the weld and heat-affected zone (HAZ). The hardness shall not exceed 280 HV1Q at any location. Test results from previous production runs of these grades may be considered to fulfill this requirement if the chemical composition and wetding procedure used are substantially the same as proposed for this order. 

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