Inspection and tests may be classified into the following categories:
a) Raw materials inspection.
b)Inspection and testing of finished bearings.
Inspection of Finished Bearing (as per IRC 83-2018):
Routine test, which includes inspection and testing (S No 1,2,& 3 below) shall be carried out by the manufacturer for all the bearings of each lot under acceptance.
Type test, which includes inspection and testing (S No 2,& 3 below)shall be carried out by detailed GREF officer on at least one bearings of each type and load capacity selected at random.The detailed GREF officer may also carry out random tests on Sno 1.
1)All bearings of the lot shall be visually inspected for absence of any defects in surface finish, shape or any other discernible superficial defects.
2)All bearings shall be checked for overall dimensions as per manufacturing tolerances.
3)At least one or a pair of bearings (depending on the requirement) of each type and different vertical load capacity selected at random shall be load tested as described below:
3a)Proof Load test: Bearings shall be load tested for a test load equal to 1.5 times the specified design vertical load in SLS condition. Load shall be applied gradually and the test load shall be held for 30 minutes. The load shall then be removed and the bearing shall be dismantled and visually examined both during and after the test. Any resultant visual defects such as physical destruction, cold flow of sliding material with reduction of projected height beyond 0.5 mm, damage of internal seal and/or extrusion of the confined elastomeric pressure pad for Pot bearing, defects / cracks at metal-to-metal contact surfaces etc. shall cause rejection.
3b)Friction test: For bearings with sliding component, friction test shall be performed to determine static coefficient of friction of properly lubricated sliding interface at constant vertical load equal to the design vertical load in SLS condition. Test assembly may comprise of a pair of bearing or a bearing and dummy sliding interface made of similar material. The horizontal load shall be applied till sliding occurs. Coefficient of friction (μ) shall be determined as the ratio of Horizontal Load at which sliding occurs divided by 2 times the applied Vertical Load (two times the vertical load in denominator represents two sliding interface due to use of a pair of bearing or a bearing with dummy sliding interface).The value of coefficient of friction shall not exceed the value specified (i.e. 0.08).
3c)Rotation test: Rotation test shall be performed on Pot bearing with properly lubricated elastomeric pressure pad under a constant vertical load equal to design load in SLS condition and for rotation value of 0.02 radian or design rotation, whichever is higher. Rotation may be applied using tapered plate having slope of test rotation value.
Proof Load test, Friction Test and Rotation Test are normally not applicable for Pin and Metallic Guide Bearings.These Test are for PTFE-POT bearing(used mostly in BRO)
Tests on raw materials :
A) Mill Test Certificates (MTC) or material test report carried out by manufacturer shall at least include the materials and control parameters described in Annexure G (IRC:83 part 3).
B) Major metallic components as specified in Annexure G (IRC:83 part 3), shall be ultrasonically tested for soundness as per Level: 3 of IS: 9565 prior to use in bearings.
C) All structural welds shall be visually checked for weld size and location as per drawing as well as controlled as per the following tests: 1)Visual test (all structural welds), 2)Liquid penetration test as per IS: 822 (all structural welds) & 3) All full penetration butt welds shall be controlled through ultrasonic testing as per IS 4260 / AWS D1.5 / ASME Section VIII.
Result :
If the raw material testing result of any material is unsatisfactory, the component(s) involving that material shall be rejected for the entire lot.
If a finished bearing fails in load test the complete bearing shall be rejected and all the bearings of that type and load capacity shall be load tested before acceptance.
All the test reports duly certified by the certified inspector shall be furnished by the manufacturer at the time of despatch of the bearing.
Certification and marking on Bearing should be done as follows:
All bearings shall have suitable index markings made of indelible ink or flexible paint, which if practicable shall be visible after installation, identifying the following information:
Name of manufacturer Month and year of manufacture Bearing designation Type of bearing Load and movement capacity Centreline markings to facilitate installation Direction of major and minor movement, if any Pre-set, if any
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