ASME STP-PT-086 pdf free download

ASME STP-PT-086 pdf free download EFFECTS OF HIGH TEMPERATURES AND FIT-UP OF RIVETED JOINTS ON STEEL RIVETS
3 RIVET TEST PROCEDURE
The hot riveting was performed in a shop environment under nearly identical conditions to a “normal” riveting job. The variation was that the transit time of the rivet from the heat source to the hole was slightly less for this project than it often is in field conditions. All steel rivets were double gunned, a procedure where two rivet guns are used and the head is formed on end of the rivet. Heating was done by electric resistance on all tests except the test group where the rivets were soaked.
These were soaked in a gas forge to provide for extended soak times of 10 minutes and 20 minutes. Temperature was monitored using an infrared heat gun. Above 1950 degrees F (1065 degrees C), getting accurate temperatures on the resistance-heated rivets was very difficult because of the rapid formation of scale.
A combination of readings from the gun and color recognition was used and both indicated at least 2250 degrees F (1230 degrees C) was attained, and probably higher temperature in some cases for the extended soak time rivets of 10 minutes and 20 minutes.
It was felt that a higher temperature made the test results even more conservative. Some rivets in the gas furnace achieved 2300 degrees F (1260 degrees C) before being driven, again resulting in more conservative results. When the rivet achieved the temperature and time requirements above, it was removed from the heat source with tongs and placed in the hole. The riveter on the head end seated the rivet with the gun off and then started that gun first to ensure that the head is seated properly on the sheet and there is no chance of the rivet being pushed out of the hole any distance.
Once the head gunner was up and running the gunner on the shank end turned his gun on and began to form the head. Upon completely forming the head, the shank gunner stopped his gun but maintained bucking pressure on the rivet. The head gunner stopped his gun after the shank gunner. This process ensured that the rivet was not hammered without bucking on the other side. Typically, when the guns are removed from the rivet, the very center of the head will be a dull red color. The plates were not pre-heated prior to driving the rivets. The rivets in the 1/8-inch (3.2 mm) oversized holes were longer than rivets for a 1/16-inch (1.6 mm) oversized hole by the amount necessary to ensure filling the hole and having enough material to form a full head on the shank end. Because more material needed to be moved in this test, the rivets were mostly devoid of any red heat color when riveting was completed. In the plates that were made to spring back, the first rivet driven was furthest from the fulcrum (9 inches) and the plates were spread approximately 1/16-inch (1.6 mm) to 3/32-inch (2.4 mm).
A fit-up like this would be an extreme case in a normal riveting job and would be considered nearly unacceptable practice. Typically, this rivet drew the plates together on the end as the rivets were formed. The next two rivets were driven in holes located between the first rivet and the fulcrum, with a plate spread of 1/32-inch (0.8 mm) to 1/16-inch (1.6 mm). The plate would have been less free to bounce than with the first rivet, however it would have rebounded more positively albeit a shorter distance. Both these rivets drew the plates closer together.
Test 3 was performed to determine if extended soak times adversely affected the rivet, and was done in the same manner as Test 2 except that the rivets were heated in a gas fired forge, and had extended soak times of 10 minutes and 20 minutes at temperature before driving. Test 4 had been in the original test program where hand riveting is accomplished using hand hammers with no pneumatic or hydraulic assistance. While this may be done on a very limited basis for historical purposes, the scope of its use in Test 4 did not seem relevant enough to justify the expenditure given limited budget constraints.