Do you know American regulation for protection in welding?

American regulation ANSI FM 4950 stablishes the essential requirements that welding pillows, welding blankets and welding curtains must meet to prevent ignition of fuels, machinery or other elements during the welding operation.

Categories

Regulation ANSI FM 4950 stablish three categories with an specific acetation criteria under its final application:

Welding pillows: must be used horizontally, must protect the area under the place where the work is done, so they must resit melted metals, direct flames or other heat sources. The tempersature of the pillow’s other side mustn’t be over 260 ºC.

Welding blankets: must be used horizontally, must protect closer areas to the working place from sprarks, flames or heat caused by welding, besides being prepared for a less intense expostion than welding pillos, the temperature of the blanket’s other side mustn’t be over 260 ºC.

– Welding curtains: different to the beforementioned categories, welding curtains must be placed vertically, must protect from sparks expelled from working areas, as well as melted metals. Although the most importain feature to take into account in welding curtains must be that they always have to maintain their flexibility and original dimensions.

Tests

To determine that each category meets the featured named before, 3 tests are done.

– Oxyacetylene machinery cutting test. This test is used to prove the behaviour of each fabric before a welding operation of stain cut. Test pieces are placed just under the cutting area, welding blankets and welding pillows are placed horizontally and curtains vertically. Test pieces placed horizontally will have 7 temperature sensors in the non exposed to fire surface.

– Paper ignition test. This testing method consists in placing a totally new paper in a metallic plate just under the test pieces placed horizontally during the oxyacetylene cutting test. Once finished, the paper is analised.

– Test to see fragility after carbonation. This test is used to verify that after oxyacetiylene cutting test, cabonised surface does not break.

These tests are done over 8 facric samples of each category, 4 samples placed weft direction (horizontally) and 4 samples placed warp direction (vertically), also this test will be done over 2 samples, one weft direction and the other waft direction, of each type after being exposed to UV beams exposure and water for 1000 hours, that is to say after an ageing process.

Behabior

Once known the test methods, to clasify each category under the protection level, the behabior before each test is specified.

– Welding pillows: During the oxycetylene cutting test, the flame mustn’t pass the fabric, the temperature of the fabric’s other side mustn’t be over 260 ºC. With the paper ignition test it must be verified that paper doesn’t have any signs of ignition. Later on, with the test to see fragility after carbonation, it is essential that the carbonised surface doesn’t break when folding the test piece. Test pieces after aging must keep the same features adter being submitted to those tests.

Welding blankets: During the oxycetylene cutting test, the flame mustn’t pass the fabric, the temperature of the fabric’s other side mustn’t be over 260 ºC. With the paper ignition test signs like decoloration of paper and holes of less than 25mm dyameter are permitted.  Later on, with the test to see fragility after carbonation, it is essential that the carbonised surface doesn’t break when folding the test piece. Any damage in the fabric caused by melted metals is excluded. Test pieces after aging must keep the same features adter being submitted to those tests.

Welding curtains: During the oxycetylene cutting test, flame mustn’t pass the fabric, nor melt or spread the flame. Vertical position must be always flexible, leaving minimum 51 mm clearance, that is to say excess fabric leant in the inferior surface of the testing system. Test pieces after aging must keep the same features adter being submitted to those tests.

 

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