DESCRIPTION: All gauges of this basic-coated electrode are extremely suitable for welding in the Vertical-Down position. The instructions covering welding with low-hydrogen electrodes and their storage should be followed. The weldments have a flat profile and are highly insensitive to cracking. Where the WELDWELL PH 27 is employed correctly, the weld metal has a finely ribbed appearance and an excellent wetting action, which eliminates undercut. In most cases, the slag is selflifting, but in all cases there is a minimum of post weld cleaning up. With the aid of the PH 27 gaps can be readily bridged in verticaldown welding. In addition, the diameters 3.2 mm and 4.0 mm are very suitable for welding root passes of single and double-vee joints in this position. As this electrode tolerates very high currents the PH 27 yields a con-siderable economic advantage in comparison with conventional low-hydrogen electrodes which have to be welded vertically upwards with a relatively low current. The high welding speeds which can be obtained, as compared with vertical-up welding, result in substantially less distortion. The PH 27 can be consumed either on AC or with the electrode connected to the positive pole, on DC. Welding Techniques How to Weld Vertically Downwards with the Weldwell PH 27. Like all Low-Hydrogen types, the PH 27 may be used with a short arc. Too long an arc will cause porosity. Use of Touch-Welding technique is not recommended, since this adversely affects root penetration, and the welding action. Welding is done with maximum current, in order that the greatest possible benefit may be derived from the use of the PH 27. The electrode is held at an angle of 80o to 90o to the direction of travel. In ship building vertical fillet joints are often limited by horizontal plates, causing a change of electrode angle to approximately 110o in the last part of the joint. Experience has proved that the slag is still easy to control above the arc, and in these circumstances the weld appearance is entirely accept-able. Making bead junctions likewise presents no problems at all. Before the arc is extinguished, the electrode is removed from the crater in the upward direction. Then the next rod is started a little below the crater, after which the latter is filled up and vertical-down welding continues. The PH 27 can be used for vertical-down welding of fillet joints in multiple layers. Overlapping runs are made if more than two layers are deposited. Should two layers be sufficient, then the second layer is welded with a slightly faster weaving motion whilst the arc is kept short. As already stated, bridging of gaps presents no problems at all in vertical-down welding. Recommended Amperages Dia. Length Amperes mm mm 3.2 305 150 max 4.0 380 200 max 5.0 455 270 max * Deposition rate at maximum Amps. AC 70V DC +
AWS A5.1 AS/NZS 1553.1
: :
E7048 H4 E4848-3 H5
WELDWELL
27 LOW HYDROGEN ELECTRODES FOR WELDING MILD AND MEDIUMTENSILE STEELS TIP COLOUR FLUX MARKING
White PH 27 7048 E4848
Approvals: American Bureau of Shipping Lloyds Register of Shipping Bureau Veritas Welding Positions: F, H, VD, OH Typical Mechanical Properties of Weld Metal Tensile Strength 507 MPa Yield Value 439 MPa Elongation(1 = 5d) 32% Impact Value Charpy 183 J V Notch at -30oC Typical Chemical Analysis C 0.04% Mn 1.15% Si 0.45% Storage (See also page 88.) Once the packet has been opened, these electrodes should be stored in a heated cabinet at a temperature of 20oC minimum and/or at least 10oC above ambient. Good ventilation should be allowed. For highest weld quality, these electrodes should be baked before use at 280oC for one hour to achieve a maximum weldmetal hydrogen level of 10ml/100g.
Deposition Rate kg/hr * 1.3 1.8 2.53
Do not redry more than three times. These temperatures should also be used to recondition damp electrodes. Use from a hot box during welding.
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