Section 1 WELDING EQIPMENT REQIREMENTS

Office 940-627-7473 Fax 940-626-4273

P.O. Box 900 Decatur, TX 76234

Hardbanding Procedures

Section 1 WELDING EQIPMENT REQIREMENTS

1.1 The welding equipment power supply must have a Direct Current (DC). Constant Voltage output capable of 24-30 Volts and of 240 to 320 Amps with the wire Positive (DCEP). Reverse polarity (DCEP) is to be utilized. Constant Current output power supplies are not suitable when applying “MIG” type wires. Some DC power supplies have the capability to deliver either a Constant Voltage (CV) or Constant Current (CC) output. If the power supply is if this type, the selector switch must be in the “CV” position.

1.2 The welding equipment should have a clean grounding system that will not resist the flow of electric current. The resistance can be seen as heat build-up in the welding lead or in its connection after a short weld time.

1.3 The equipment should have the ability to grip and rotate the tool joint under the welding torch concentric to within .030” (0,76mm) and at a constant uniform speed of between 60 and 200 seconds per revolution. The tool join O.D. is the factor that determines the speed at which to rotate the tool joint.

1.4 The equipment must have the ability to move the welding torch from vertical center so that welding takes place on the uphill side if the tool joint as it is being rotated. Further, the offset adjustment must be positioned correctly so that the electrode wire, during welding, is NOT to far forward to top-dead-center and allows the welding arc to burn “within the molten puddle”. Welding within the molten puddle can cause porosity and lack of fusion with the parent metal.

1.5 The equipment must have the ability to oscillate the welding torch at a standoff or “stick –out” distance of 1” to 1-1/8” (25, 4mm to 28, 6mm), from the welding surface and at the approximately 50 to 90 oscillations per minute. This distance is measured from the torch tip and not the nozzle cover. A stick-out distance less than 1” (<25, 4mm) can sometimes cause turbulence of the gas flow, at the nozzle cover, which can cause porosity in the weld bead.

1.6 The equipment must be able to move the torch, parallel to the joint axis, for a minimum distance of 12”.

1.7 Welding equipment should include a wire feed system capable of feeding the wire through the torch at a variable, uniform speed without damaging the surface or the shape of the wire. Special wire-feed rollers designed for feeding soft-skinned, flux-cored wire should be utilized. The wire feeder should also have a wire straightener to remove, as best as possible, the normal “cast” of the wire.

1.8 A shielding gas of 98% Argon and 2 % Carbon Dioxide must be supplied to the arc when welding. The regulated flow of gas must be controlled to deliver 30 to 35 CFH to the arc area. During windy conditions, when operating portable hardband units in pipe yards or at rig locations, every precaution shall be taken to protect gas flow at the nozzle, inside the torch cabinet from being blown away from the arc when welding.

Section 2 MATERIAL PREPARATION

NOTE: Preparation of the hardband area must be performed to minimize, if not eliminate, foreign matter become an impurity in the molten weld puddle and to ensure a good fusion bond with the parent metal. Preparation must be performed when applying hardbanding onto either new or used material.

2.1 Visually inspect the weld surface of all the tool joints or hardband areas to ensure they are clean and free of all foreign matter such as rust, dirt, grease, oil, paint or pipe coating.

2.2. The threaded connections should be cleaned of all thread lubricants or storage compounds. This will ensure a much cleaner welding process and eliminate the probability of the lubricant or compounding igniting during pre-heat.

2.3 Preheat the hardband area to the appropriate temperature rang.

It is strongly recommended that preheat temperature be measured with digital, electric pyrometer. The minimum acceptable requirement is the use of two tempstiks; one for each of the minimum and maximum temperatures of the range. The unit operator must ensure that the desired preheat temperature range is controlled.

NOTE: If tempstiks are used on the prepared hardband surface, the residue left by the tempstik must not be excessive. If the residue is excessive, it must be removed prior to welding. If not, the residue can become an impurity that may affect the fusion bond of the hardbanding to the prepared surface.

2.4 The preheat area needs to be buffed with a grinder equipped with a wire cup brush.

Section 3 HARDBAND APPLICATION

3.1 Placement and number of bands on new joints are to be specified by the customer.

Reapplications of hardbands are to be applied over the existing hardband area unless a change is specified by the customer.

3.2 The unit operator should adjust the hardband equipment to attain a flat or slightly convex weld profile. Each weld bead should overlap the previous weld bead ~1/8” and consistently “tie-in” with the edge of the preceding weld bead.

3.3 The tungsten particles are to be dropped from the feed tube so as to penetrate the weld pool.

Section 4 COOLING

4.1 The applicator must “slow-cool” the hardbanded tool joint. To ensure the required slow cooling, the tool joints need to be wrapped immediately in thermally insulated blankets or insulation. The blankets or insulation shall remain on the tool joint ends unit the tool joint has cooled down to less the 150F.

Section 5 INSPECTIONS

5.1 Cracks that are oriented perpendicular to the weld bead and normally as close as ½” or as far as 3’ apart are considered acceptable.

5.2 Oblique cracks occur and are acceptable as they may intersect perpendicular or circumferential cracks. Sometimes, they are a continuation of a perpendicular crack.

5.3 Any crack found that is wider the 1/16” shall be rejected as this may be an indication of rapid cooling of the hardbanding after application.

NOTE: After cool down and inspection the hardband area shall be painted as a rust inhibitor for transport and storage.

Section 6 Water Cooling

CAUTION: When capping pipe - with water inside - extreme pressure WILL build up during pre-heating and welding. Serious injury can result when removing the plugs due to steam pressure inside the pipe. ONLY use a vented plug on the opposite end of the pipe that is being welded.

6.1 When customers specifications call for reducing the normal temperature the core pipe will reach during pre-heating and welding, 2 to 3 gallons of water is pumped into the pipe and the ends are capped to keep the water inside the pipe during the hardbanding process.

6.2 Metal plugs/caps must be used on the welded end of the pipe and securely tightened to prevent water from dripping into the hardband unit. Use caution and wear protective gloves to remove them to prevent burns.

6.2 When the water is drained after hardbanding it must be recovered to prevent any contamination that may exist inside the pipe (including pipe thread lubrication) from contaminating the ground on the jobsite.

6.3 Water that is drained can be reused however any used (contaminated) water that is remaining after the job is finished must be disposed of in an environmental safe manner, or properly stored for the next job.

Note: 35 ft of 4.5 inch drill pipe can hold 15 gallons of water. The volume of steam is 1,603 times the volume of an equal mass of liquid water. One Gallon of water produces 223 cubic feet of steam. Experience has proven that the best method – when using water – is to elevate the racks opposite the hardband unit, about 4 inches. This will prevent water from running out the opposite end -- and an end cap will not be needed on that end – thus eliminating any risk of high pressure build up inside the pipe.