Pot Bearing Specification 2002 11 En

Technical Specifications for mageba Pot Bearings

Prepared: DN Revised: GM Approved: GM

Revision: 01 Date: 5.11.2002 Page: 1/4

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Technical Specification: mageba Pot Bearings

1. DESIGN REQUIREMENTS

Design according to BS 5400 and this specification.

The bearings shall be designed to be replaceable by jacking up the bridge deck by maximum 10 mm. Bearing size must respect the pier sizes.

2. SLIDING MATERIALS

2.1 PTFE

PTFE material must be pure PTFE according to the following Standard:

pure polytetrafluorethylene free sintered without regenerated or filler materials mass density: 2140 to 2200 kg/m3 tensile strength: 29 to 40 MPa elongation at break: ≥ 300% ball hardness: H132/60 = 23 to 33 MPa

The PTFE must have dimples. Flat PTFE is not allowed. Dimple pattern must be in that manner, that in the main sliding direction there are no areas without dimples (dimples in single rows shall not be allowed). Dimple pattern shall be in accordance with the following figure:





2.2 Austenitic Steel

For stainless steel the following material has to be used:

Austenitic Steel: X 5 CrNiMo 17 12 2 material no. 1.4401 Surface roughness Ry5i: ≤ 1µm ISO 4287-1/2

Thickness of austenitic steel:

Sliding sheet welded to sliding plate: 1.5 mm Sliding sheet bolted to sliding plate: 2.5 mm

2.3 Lubricant

All dimples have to be filled by well proven silicon grease. The following material specifications for the lubricant shall be met:

worked penetration: 26.5 to 29.5 mm acc. ISO 2137 dropping point: ≥ 180 °C acc. ISO 2176 oil separation after 24h at 100°C: ≤ 3% (mass) oxidation resistance pressure drop after 100h at 160°C: ≤ 0.1 MPa pour point of base oil: below –60 °C acc. ISO 3016

silicon oil content: ≥ 80% (remainder lithium soap)

2.4 Tests

The sliding materials and its combination must have proven in tests (according to prEN1337-2), that it is suitable for the use in sliding bearings. The sliding distance is at least 15'000 m and the following sliding coefficients have to be fulfilled at a pressure of 30 MPa:

0°C: ≤ 2% +21°: ≤ 2% +35°: ≤ 2%

2.5 Guide Bars

All guide bars shall have a composite material (CM) sliding on an austenitic steel sheet (specification acc. to 2.2). Only steel to steel contact shall not be allowed.

The composite material shall consist of three layers with a bronze backing strip and a sintered interlocking porous matrix, impregnated and overlaid with a PTFE / lead mixture:





Bronze backing: CuSn 6 Bronze interlayer: CuSn 10 Surface Layer: PTFE/Pb (Pb 20%, remainder PTFE)

3. ELASTOMERIC PAD

The elastomeric pad shall be natural rubber in accordance with ISO 6446.

4. SEALS

Seals for rubber pads must have proven its high durability. Suppliers must demonstrate that the seals have passed successfully a wear test of more than 2000 m sliding way along the pot wall. The tests have to be performed according to prEN1337-5.

Tribologically not suitable material combinations like stainless steel seals against steel pot shall not be allowed.

5. CORROSION PROTECTION

Only mild steel with suitable corrosion protection system shall be used. No weathering steel shall be allowed.

The inside of the pot and the side of the piston towards the rubber pad must be free of paint.

6. MANUFACTURING

The bearings shall be manufactured by a specialised manufacturer, with at least 20 years experience in this field. The manufacturer shall demonstrate, that he has manufactured bearings similar according to the given specifications and requirements. All manufacturers have to be approved by the client.

The pot must be manufactured of one single piece. No welded or bolted connections between pot ring and bottom plate shall be allowed.

Pointers and scales have to be provided at least at one moveable bearing on each pier.

7. QUALITY CONTROL

The supplier shall have a QA-System according to EN ISO 9001. The QA-System must be in use for more than 6 years and must have passed successfully at least one repetition audit.

The production of the bearings must be supervised at least 4 times a year by an independent test authority with knowledge in the field of bridge bearing production. The test authority must be approved by the client.

8. INSTALLATION

The manufacturer shall submit an installation manual with the drawings.





9. TESTING

Bearing tests have to be performed according to BS 5400 Section 9.2 sub clause 7.2 (b) and (c). The bearing shall be considered satisfactory when test results comply with section 9.2.

Should the manufacturer make available well attested and documented information on similar bearing types, tests according to BS 5400 section 9.2 subclasses 7.2 (b) and (c) shall not be necessary.

Pot Bearing Specification 2002 11 En

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