Title:
Dual type blowout preventer
United States Patent 2690320


Inventors:
Shaffer, Donald U.
Wilde, Arthur E.
Application Number:
US28483252A
Publication Date:
09/28/1954
Filing Date:
04/28/1952
Assignee:
SHAFFER TOOL WORKS
Primary Class:
Other Classes:
251/212, 277/325
International Classes:
E21B33/06
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