Snatch Blocks Information

  Competition Crosby

DESIGN

The theoretical reserve capability of a snatch block should be at least 4 to 1. Known as the DESIGN FACTOR, it is usually computed by dividing the ultimate load by the working load limit. The ultimate load is the average load or force at which the block fails or no longer supports the load. The working load limit is the maximum mass or force which the product is authorized to support in general service. The design factor is generally expressed as a ratio such as 4 to 1. Also important in the design of snatch blocks is the selection of proper steel used in components and consideration as to fatigue life..

Ask: Are their snatch blocks metric rated?

Ask: What is the metric design factor?

Ask: Are their snatch blocks fatigue rated?

Most do not provide metric ratings with a design factor of 4 to 1, nor fatigue rated snatch blocks.

McKissick and Lebus snatch blocks are dual rated with a design factor of 4 to 1 for metric and 4.5 to 1 in short tons.McKissick and Lebus snatch blocks incorporate the proper selection of steel and are also fatigue rated.

END FITTING CONNECTIONS

Interchangeability of end fittings is important, and should be easily achieved without disassembly of the block. It is also important that end fittings are quenched and tempered in order to reduce the risk of brittle, catastrophic failure.

Ask: Are the end fittings forged, quenched and tempered?

Ask: Are the end fittings inter-changeable?

McKissick and Lebus snatch blocks use genuine Crosby forged, quenched and tempered hooks and shackles.

BLOCK CONSTRUCTION

The block performance depends greatly on the sheave and block construction. All steel construction, including side plates, pins, and sheaves is desirable. Bronze bushings are recommended for slow line speeds and frequent use. Roller bearings are recommended for faster line speeds and more frequent use at greater loads. The ability to individually lubricate all sheaves is essential. Secondary securement of bolt connecting the end fitting to the block is recommended.

Ask: Are their blocks all steel construction?

Ask: Do their blocks have secondary securement of the pins?

Ask: Are all sheaves individually lubricated?

McKissick and Lebus snatch blocks are of “all steel” construction. They also have a secondary end fitting securement system. In addition, sheaves are individually lubricated.

FULL LINE IDENTIFICATION

The availability of a full range of snatch blocks is essential to insure that the appropriate block is available for a specific application. All snatch blocks must be identified by type, size of block, size of wire line to be used, working load limit, and the manufacturer’s name boldly marked on the product.

Ask: Do they have a full range of snatch blocks?

Ask: Are their snatch blocks properly marked with critical information?

Most competitors do not have the full range of snatch blocks that Crosby offers.

McKissick and Lebus provide the most complete line of snatch blocks in the industry. All McKissick and Lebus snatch blocks are identified by type, size of block, size of wire line to be used, working load limit (in both metric and short tons), and the manufacturer’s name boldly marked on the product.

STANDARDS ORGANIZATION

All snatch blocks utilized in the oilfield should be manufactured by a source that is both API Q1 and ISO 9001 certified.

Ask: Are they API Q1 certified?

Ask: Are they ISO 9001 certified?

Most competitors are not API Q1 certified or ISO 9001 certified.

Crosby’s McKissick plant is API Q1 certified. McKissick is also certified to ISO 9001 standards by Det Norske Veritas (DNV).

APPLICATION INFORMATION

Detailed application information will assist you in the proper selection of snatch blocks. This information is most effective when provided at the point of application, as well as in supporting brochures and engineering information. A formal application and warning system that attracts the attention of the user, clearly informs the user of the factors involved in the task, and informs the user with the proper application procedures is needed.

Ask: Does each snatch block have the application and warning information attached to it?

Most competitors do not have application and warning infomation with each snatch block.

Crosby provides detailed application and warning information attached to each snatch block.

Crosby Value Added

  • Dual rated: To meet the requirements of both short tons and metric tons.
  • Metric rating: McKissick® and Lebus® snatch blocks are metric rated to a design factor of 4 to 1. Since they are metric rated, with a world class design, they are applicable to worldwide use without conversion.
  • U.S. rating: When compared to other blocks which are rated in short tons, the design factor of McKissick® and Lebus® snatch blocks are 4.5 to 1.
  • Fatigue properties: McKissick® and Lebus® snatch blocks are fatigue rated. The blocks are designed to meet specific fatigue performance levels. They meet the requirements for the new Euronorm Standards: 20,000 cycles at 1-1/2 times the Working Load Limit.
  • Latch Kits: McKissick® and Lebus® snatch blocks, utilizing a hook as an end fitting connection, can be equipped with latches. Application information: Application and warning information for tackle block systems is attached directly to each block. In addition, each block has a product warning sticker attached directly to it for the purpose of giving specific warning instructions about the block.
  • Lock nut: McKissick® snatch blocks have a special high performance lock nut on the nonmoveable side plate for securing the sheave pin.
  • Sheave and wire line: Sheaves for McKissick® and Lebus® snatch blocks have a machine formed groove.
  • Secondary Securement Systems: McKissick® and Lebus® snatch blocks are designed to incorporate a secondary securement system which retains the end fitting connection bolt when the block is in the closed position. In addition, a patented system retains the end fitting connection bolt when the block is in the open position, thus eliminating the loss of block parts.
  • RFID Equipped: All snatch blocks with sheave diameters of 4-1/2” and larger are equipped with RFID chips to provide a streamlined and automated approach to the inspection process.

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