Survey Caps for Rebar and Pipe
A good survey cap for rebar or pipe must virtually eliminate dissimilar metal corrosion. What typically happens is that the survey cap loosens over a short period of time. This confirms metallurgical theory. Aluminum is less "noble" than steel and an electrical current will actually flow from the aluminum (+) to the steel (-). Corrosion will occur in the anode (+) area of the battery like combination of metals in the presence of moisture (air or soil acting like an electrolyte).
Berntsen originated the insulator/wedge which effectively isolates the survey cap from the steel and de-forms around the ribs of the rebar or the outside of the pipe. The hex shape fills with the deformed plastic material and the survey cap is locked on with a super tight compression fit. Great force is required to remove the cap.
Berntsen International, Inc., P.O. Box 8670, Madison, WI 53708-8670. Tel: 800-356-7388; Fax: 800-249-8549.