Crosby® Value Added
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.
The Competition
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.
The Competition
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.
The Competition
AskHow do they achieve the performance required with a split or cast sheave?
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 Indentification
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 Wireline to be used, working load limit, and the manufacturer’s name boldly marked on the product.
The Competition
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 Wireline 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.
The Competition
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.
The Competition
ASK: Are they API Q1 certified?
ASK: Are they ISO 9001 certified?
Most competitors are not API Q1 certified or ISO 9001 certified.
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.