Rev. 1-31-97

BEARING ASSEMBLIES

726-B-044

The Standard Specifications are revised as follows:

 

SECTION 726, BEGIN LINE 1, INSERT AS FOLLOWS:

SECTION 726 -- BEARING ASSEMBLIES

726.01 Description. This work shall consist of furnishing and installing bearing assemblies in accordance with the applicable requirements of 915.04, the details shown on the plans, the manufacturer's recommendations, or as directed.

726.02 Materials. Materials shall be in accordance with 915.06.

726.03 Construction Requirements. Masonry plates for polytetrafluoroethylene bearings shall be perfectly level. The tolerance between the top face of the masonry plate and the bottom face of the top plate shall be a maximum of 1.6 mm (1/16 in.), measured at the ends of a diameter of the bottom plate of the bearing assembly. Other dimensional tolerances shall be as shown on the plans or in accordance with 915.04(d).

726.04 Method of Measurement. This work will be measured by the number of bearing assemblies complete in place.

726.05 Basis of Payment. This work will be paid for at the contract unit price per each for bearing assemblies of the type shown on the Schedule of Pay Items.

Payment will be made under:

Pay Item ----- - - - - ----------------------------------Pay Unit Symbol

Bearing Assembly, ______. . . . . . . . . . . . . . . . . . . . . . . . . . EACH
- - - - - - - - - -- -- - -type

 

The costs of having a manufacturer's representative at the job site during installation, and all necessary incidentals shall be included in the cost of this work.

SECTION 915, AFTER LINE 309, INSERT AS FOLLOWS:
915.06 Polytetrafluoroethylene Bearing Assemblies. A copy of the manufacturer's design manual shall be submitted for approval when directed.

All steel components shall be in accordance with ASTM A 709M Grade 250 (ASTM A 709 Grade 36) unless otherwise shown on the plans. Where these assemblies are to be used in conjuction with self-weathering steel bridges, the steel components shall be in accordance with ASTM A 709M Grade 345W (ASTM A 709 Grade 50W). Stainless steel mating surfaces shall be 14 gage minimum ASTM A 240 type 304 sheets with a maximum surface roughness of 20 Rms.

The polytetrafluoroethylene shall be 100 percent virgin unfilled polymer or 15 percent glass filled and etched on the bonding side. The properties of the polytetrafluorethylene shall be in accordance with the following:

REQUIREMENT TEST METHOD VALUE
Hardness at 78ºF (25ºC) ASTM D 5212 50-65 Durometer
Tensile Strength, minimum ASTM D 638 17.24 MPa (2,500 psi)
Elongation, min. percent ASTM D 638 200
Specific Gravity ASTM D 792 2.1 to 2.3

Polytetrafluoroethylene, where required, shall be bonded to grit blasted steel. The polytetrafluoroethylene guides shall be bonded and mechanically fixed into place. The bonding compound used to bond polytetrafluoroethylene or elastomeric pads to steel plates shall be in accordance with ASTM D 429, Method B.

All steel surfaces exposed to the environment shall be zinc metallized and shall be 175 :m (7 mils) thick in accordance with CSA G-189, or painted with structural primer in accordance with 908.02(d). The finish coat for painted steel shall be in accordance with 909.02(b). The color shall be in accordance with Federal Color Standard 595a, color No. 30045.

All required materials shall be covered by a type B certification in accordance with 916.

SECTION 916, AFTER LINE 57, INSERT AS FOLLOWS:

Bearing Assembly Materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 915.06