AWS D10.11 – D10.11M pdf free download

AWS D10.11 – D10.11M pdf free download.Guide for Root Pass Welding of Pipe Without Backing.
nozzle weld. A nonstandard term for a weld between two pipes in which a hole is made in one pipe, and the other pipe is welded onto the first pipe at the hole at a predetermined angle to provide an alternate fluid path.
purge. A standard term for the introduction of a gas to remove contaminants from a system or provide backing during welding.
purge caps. Devices made of any suitable material that can he used to seal the ends of pipes for purging.
purge dams. Barriers made of any suitable material that can be placed inside pipes to contain the purge gases within the weld area. They may be water soluble or of some other type.
walking-the-cup. A technique for manipulating the torch when manually welding groove welds. With this technique, the electrode extension is adjusted to allow the proper arc length while the edge of the shielding gas nozzle rests on both groove faces of the joint. The torch is manipulated using a wrist motion in which the nozzle (cup) is rotated at a slight angle to the axis of the root opening, increased pressure is exerted on the leading groove face while the nozzle is rotated causing forward progression. Subsequently the nozzle is rotated and increased pressure is exerted on the opposing groove face. The nozzle is again rotated causing further forward progression. This motion is repeated so that the cup appears to he walking’ along the groove faces while the arc oscillates smoothly across the joint.
water-cooled torch. A welding torch where the primary cooling medium is the flow of waler or other liquid coolant through the torch.
4. Preparations for Welding
4.1 Cleanliness. Cleanliness is important in all welding operations. hut it is especially important in root pass welding. Cleaning should be done on the groove faces and a minimum of 25 mm [1 ml of the base metal on both the inside and outside surfaces of the pipe. All parts of the joint should be free of grease and oil, which should be removed by use of a suitable solvent. A suitable solvent is one that does not leave a residue and is not harmful to the welder or to the weldment. Most solvents require good ventilation, and many are flammable; therefore, proper precautions should be taken. Grinding or other mechanical means should be used to remove all paint, scale, rust, and dirt.
Grinding and cleaning operations should be done just prior to welding. After cleaning, the pipe should he handled so as to preserve cleanliness.
4.2 Purging 4.2.1 Purging Applications. An internal gas purge is required for stainless and nonferrous piping systems (except aluminum) if a smooth root surface is to be obtained. Carbon steels and low alloy steels containing less than 5% chromium can be welded using an open root groove without the use of an internal gas purge. How- ever, purging of joints is highly recommended when the chromium content of the weld metal exceeds 2% or when using a consumable insert since purging reduces the occurrence of defects and the excessive oxidation of the resultant root bead. Inert backing gas should always be used for consumable inserts of any material other than carbon steel and when using Class 1 or 2 inserts. It should be noted that purging will increase welding speed significantly when used during welding steels that do not normally require purging, such as carbon and low alloy steel.AWS D10.11 – D10.11M pdf download.