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Several years ago, Southern Plains Fabrication did an analysis of the previous triangular slipbase housing styles. The company discovered several main flaws in slipbase housing designs, namely:

• Sign posts work loose within the set screw design triangular slipbase housing, leading to problems with signs turning
• Set screw triangular slipbase housings deform sign posts because the set screw design maintains only three small points of contact to hold the post in place

Based on this information, Southern Plains Fabrication designed a triangular slipbase housing that does not fail in these areas. Additionally, the SPF housing improves on other minor problems with previous slipbase housings. The points that make SPF housings stand apart from other designs include the following:

• Sign posts do not loosen or rotate within the SPF housing – the clamping bolts do not loosen with time because they are not in direct contact with the sign post
• SPF housings do not affect the structural integrity of sign posts – the housing maintains full contact all the way around the sign post, decreasing the force on the post per unit surface area
• One wrench size installs the housing – the two clamping bolts and the three bolts used to bolt the housing to the ground stub are all the same size
• SPF housings are purchased as a kit, including all parts needed to attach the sign post to the stub – for kit contents, see “What the Kit Contains” below
• SPF housings can be used as either a sign post housing or a ground stub when inverted and 2 1/2” X 36” Schedule 80 pipe is inserted and concreted into the ground
• SPF housings are made of steel, not ductile cast iron
• The housing contains no threads, eliminating the possibility of thread failure.
• Easier to install than other designs – SPF housings can be mounted on the ground stub before the sign post is installed

SPF triangular slipbase housings have been crash tested and meet NCHRP Report 350 standards. They can be used with Schedule 80 or 10 BWG (Birmingham Wire Gauge) sign posts. SPF housings will bolt to all other commercially manufactured triangular slipbases; no matter the origin of the ground stub, SPF housings can be mounted on them. Even if a sign post has been damaged by a set screw housing, the sign post can still be used in a SPF housing.

In cases where the sign post system has been impacted, with the exception of the bolt keeper, all pieces of the system can be reused. The SPF housing absorbs the energy of the impact, without damaging the housing, and prevents damaging all other parts of the system. So in cases of sign impact, cost of repair includes only one bolt keeper.

1 – Southern Plains Slipbase Housing
5 – 5/8 – 11 X 2 ½ bolts
5 – 5/8 – 11 2H nuts
9 – F – 436 washers
1 – bolt keeper
1 – assembly drawing

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