Class Code: 6236
Per NCCI's Scopes Code Description:
Code 6236 is applied to a specialist contractor engaged in the installation or recovery of casing at oil or gas wells and includes incidental cementing work when performed by the casing contractor’s crew.
Installation of casing consists of three basic operations—stabbing, making up and lowering casing into the hole. After “stabbing” or guiding the end of the casing into a coupling or tool joint on the preceding segment, the “make-up” or assembly process is completed with the use of hydraulic or “power” casing tongs to spin up and tighten each joint. The joint may be welded to prevent seepage. Before lowering into the hole, the casing crew may also attach devices called “centralizers” and “scratchers” on the outside of the casing. Centralizers have a bowed-spring arrangement to center the casing in the hole after it is lowered and this makes for a better cement job later. Scratchers are a series of stiff wire rings which surround the outside casing. By turning or moving the casing string up and down as it is lowered into the hole, scratchers remove the cake formed by drilling fluids (mud) on the hole wall so that cement can bond solidly to the formation.
After the casing string is run, it is cemented in place. Oil well cementing service companies are usually called in to perform this work and Code 6206 would apply to those specialists. However, such work may also be performed by or with the assistance of the casing or drilling crew. Casing is usually installed while the drilling rig and equipment is still over the hole with the aid of special elevators, tongs and heavy duty slips to hold the casing in place while sections are joined. The drilling crew derrickman and roughnecks may assist the casing crew in the installation process. Code 6235 is applicable to casing operations when performed by a drilling contractor or to a casing contractor who also performs drilling operations at a particular job or location.
Casing recovery, removal or “pulling” operations involve raising the casing out of the hole, uncoupling the casing sections, and lowering the casing onto the ground next to the hole. The lower sections of casing may require dislodging or perforating before being pulled and this may be accomplished by using mechanical rippers or explosive charges. After the casing has been removed, the well is plugged with cement. Equipment utilized in recovery operations may include, but is not limited to, hydraulic jacks, pulling units, spinning ropes or chains, break-out tongs, sucker rods, mechanical rippers, and demolitions.
Extra-Territorial Classification Guidelines:
The following material was developed by NCCI to be used as a guide by auditors and underwriters in the determination of premium for contracting (construction risks) with extra-territorial employments where no company guidelines have been established for this purpose. Construction classifications are indicated by the addition of a construction code symbol (•) next to the classification code number.
When a portion of the operations of a risk are insured in a monopolistic state fund, consider the special rules and requirements that may exist in such cases.