Traveling block

API Standard 4A (superseded by Standard 4F) provides rating of derrick capacities in terms of maximum safe load. This is simply the load capacity of a single leg multiplied by four. It does not account for pipe setback, wind loads, the number of lines between the crown block and the traveling block, the location of the dead line, or vibratory and impact loads. Thus, it is recommended that the maximum safe static load of derricks designed under Standard 4A exceed the derrick load as follows ... 

In general, = W n if the deadline is attached to one of the derrick legs, and F = W 2n if the deadline is attached between two derrick legs, n is the number of lines between the crown block and traveling block. The formula for F assumes that no single leg shares the deadline and fastline loads. 

Maximum rated static hook load for a specified number of lines to the traveling block. 

Rated static hook load for wind velocities varying from zero to maximum rated wind velocity with full rated setback and with maximum number of lines to the traveling block. 

A hoisting system, as shown in Figure 4-8, is composed of the drawworks, traveling block, crown block, extra line storage spool, various clamps, hooks, and wire rope. 

Normally, a hoisting system has an even number of working lines between the traveling block and the crown block. The fast line is spooled onto the drawworks hoisting drum. The dead line is anchored to the rig floor across from the drawworks. The weight indicator is a load cell incorporated in the dead line anchor. 

The mechanical advantage of the hoisting system is determined by the block and tackle and the number of working lines between the crown block and the traveling block [7]. 

When the hook load is lifted, friction losses in crown block and traveling block sheaves occur. It is normally assumed that these losses are approximately 2% deduction per working line. Under dynamic conditions, there will be an efficiency factor for the block and tackle system to reflect these losses. The efficiency will be denoted as the hook-to-drawwork efficiency (e, ). The force in the fast line under dynamic conditions (i.e., hook is moving) will be... 

It is required that the drawworks input power be able to lift 600,000 lb at a rate of 50 ft/min. There are eight working lines between the traveling block and the crown block. Three input power systems are available 1,100, 1,400, and 1,800 hp. Which of the three will be the most appropriate The value of e is... 

Traveling blocks A heavy duty pulley system that hangs in the derrick and travels up and down with the hoisted tools. It is connected to the crown block with a wire rope that ultimately runs to the hoisting drum. 

Block-to hook adapters A metal piece that attaches to the bottom of the traveling block and serves as the mount for the hook. 

Drilling hooks The hook that attaches to the traveling block to connect the bail of the swivel. 

Tubing and sucker rod kooks Hooks connected to the traveling block for tubing and sucker-rod hoisting operations. 

Deadline tiedowns The deadline is the nonmoving end of the wire rope from the hoisting down through the crown and traveling blocks. This end is anchored at ground level with a tiedown. 

Spacer Plates. Spacer plates of traveling blocks, not specifically designed to lend support to the sheave pin, shall not be considered in calculating the rated capacity of the block. 

Sheave Pins. In calculations transferring the individual sheave loads to the pins of traveling blocks, these loads shall be considered as uniformly distributed over a length of pin equal to the length of the inner bearing race, or over an equivalent length if an inner race is not provided. 

Block Bearing Rating. The bearing rating of crown and traveling blocks shall be determined by... 

Figure 4-16. Traveling block and hook bail contact surface radii [9].

NOTE The above caaes apply also where the rope is dead ended at the lower or traveling block or derrick floor after passing over a dead sheave in the crown. 

Figure 4-75. Typical reeving diagram for 14-line string-up with eight-sheave crown block and seven-sheave traveling block left-hand reeving [11],...

Minimum fleet angle from the drawworks drum to the first sheave of the crown block, and from the crown block sheaves to the traveling block sheaves. 

Recommended Reeving Arrangements for 12-, 10-, 8-, and 6-Line String-ups Using 7-Sheave Crown Blocks with 6-Sheave Traveling Blocks and 6-Sheave Crown Blocks with 5-Sheave Travelina Blocks 1111... 

Sheaves conforming to the specifications (Specification 8A) shall be marked with the manufacturer s name or mark, the sheave groove size and the sheave OD. These markings shall be cast or stamped on the outer rim of the sheave groove and stamped on the nameplate of crown and traveling blocks. For example, a 36-in. sheave with 1 in. groove shall be marked... 

The derrick is the frame structure from which the drill string in suspended on the drill line using a system of pulleys known as the crown and traveling blocks when working in the borehole. The drawworks or hoist is the key piece of equipment on the rig and is used to raise and lower the drill string and control the weight being applied by the drill bit on the rock face on bottom. 

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