For the Transformer repair, adjustable wrenches are divided by numbers from 1 to 6. The first number has a sponge solution up to 19 mm, the second up to 30, the third up to 36, the fourth up to 41, the fifth up to 46 and the sixth up to 50 mm. The complexity of work when unscrewing and screwing bolted joints is significantly reduced with the use of pneumatic wrenches. From www.surplec.com you can have the best support here.
The Bolting Process
The bolting of transformer bolts that do not have an expander, a safety pipe and other fittings begins with the detachable connection of the lid to the tank. For transformers, on the cover of which these devices are mounted, a gas relay is first dismantled, and then a safety pipe, an expander, switches drives and other devices. To dismantle the gas relay, four bolts are unscrewed on each side of the relay. In this case, the relays are supported by hand or a wooden lining is placed under it. Release the “a bolt, the relay housing is moved parallel to the flanges and remove it. The openings of the relay are closed with temporary blank flanges made of electric cardboard, which are secured with freed bolts. The relays are carefully placed on the shelf or immediately sent to the laboratory for inspection and testing.
The active part, together with the cover, lifted by universal strings
The device of two-branch slings:
A – type GSK from a steel rope, b – sling type GSS from a chain; 1 – a hook with a safety bracket, 2 – a sling branch, 3 – a mooring ring to the lifting mechanism
The device universal slings type USK:
a – with loops, b – circular
The expander is dismantled in the following order: the oil line leading to the gas relay is disconnected from it, the oil indicator glass is closed with a temporary shield from a board or plywood, tying it to the oil indicator fittings, the expander is slung with a hemp or steel sling depending on the weight, the bolts securing the expander brackets are unscrewed, and lower it to the floor. Extenders of large transformers are removed by a lifting mechanism. At substations, a crane is used for these purposes.
To prevent dirt and moisture from entering the expander, all openings in it are closed with plugs and temporarily sealed with old rubber gaskets. Then, with two open-end wrenches, the bolt fastening of the lid is unfastened: with one wrench, unscrew the nut located under the side of the lid, with the other hold the bolt head from turning. Bolts are equipped with nuts and washers and, slightly moistened with kerosene, stored in a metal container until assembly.
The next most critical technological operation is the slinging of the active part and its removal from tank 1. If it is not fastened with the cover in, first remove the cover, if fastened, for example with lifting studs 2, then the active part together with the cover is lifted with slings 5, hooked on the frames 4 and attached to the hook 6 of the lifting mechanism. For slinging the active parts of small mass for two eyebrows, two-branch slings are used, made of flexible grades of steel ropes, or chains, for four eyebrows four-branch ones.