Wellheads With the surface hole drilled and casing set we can now start to build the wellhead. There are many types of well head I have decided to make my own,  However they all do the same job and are basically the same. The wellhead is a weld on the red arrows indicate the area to be welded Such welding must be done by a graded welder as it will be tested after too 500 psi. Note the small test plug between the welding. The important points to remember while this is being done. The pipe must be heated to the proper tempter and a cover to be installed over the top. This is to stop any water from dripping onto the hot welds. As this is the starting point it has to be installed level a bad job here will cost a lot of time later. All the welding area must be clean and free of grease. time spent planning and preparing is not wasted. I wont go into the safety precautions as most are standard  The weld must be allowed to cool on it own.  Many well heads have failed the testing  not because of bad welding but inpatients, Give the weld time to cool before attempting  to test it. After the wellhead has been tested the casing head is install, this is flanged together with a steel gasket being installed between the two flanged before they are bolted together. The casing head is then installed. Care must be taken not to damage the seals on the x-bushing. Once installed the flange is hammered up to the predetermine torque. Once tightened it has to be tested. The "P" seals inside attached to the x-bushing are energized by pumping in solid sticks of plastic, dependent on the size of the casing will be the number of stick pumped. It is also important to remember that only so many sticks will go into a given size x-bushing. Once achieved the seals will pressure up. Exceeding the recommended pressure will do one of two things. Damage the seals, in this case you will have to replace the seals. Or collapses the casing. In this case you will be replaced. Word of warning if you intend to use an air pump "NOT RECOMMENDED" then you had better stay with the job. you may not be as well liked as you think. The configuration described above is a basic standard casing program It consist of 30 inc drive pipe. 20 inc surface pipe and 13-3/8 intermediate casing. The next section of the hole could be drilled as 12-1/4 or 10-3/4 and is dependent on the over all well plan. However sooner than make this page too long the next 2 stages will come under BOP testing and liner running Crossover Seal Bushing Preparation ............................YB' Seal Bushing To allow the use of casing and tubing spools over more than one casing size, it is necessary to use a crossover bushing. Cameron's standard for these applications is the 'YB' bushing. This uses two seals between the O.D. of the bushing to spool seal bore, and a single 'P' seal in the bore of the bushing. Plastic packing is injected through a port in the flange O.D. to energies the bushing onto the chosen casing. These bushings are available for flange sizes of 9" through 20" nominal, and for casing sizes of 4.1/2" through 13.3/8". Moderate service conditions are covered, with pressure ratings up to 10000 psi. The bushing fits into the bottom of the casing head before the head is installed on the cut off stump of casing and is held in place by a snap ring. All the sealing elements are on the bushing. Before installing the recess in the well head should be cleaned and a thin coat of oil applied. When the casing stump is ready it too should have a coat of oil. the ring grove on both mating flanges should be dry clean and a clean dry new ring installed. Oil can then be put into the void around the casing stump but must not go into the ring grove  Both the bushing and the head are then slipped over the stump and lowered carefully into position so as not to damage the inner seals. Once in place both flanges can be made up remembering to keep the gap even. Once tight,  tight. the seals can be energized.