PTFE Sliding Bearing Installation Checklist: Guides, Orientation and Temporary Locking

Pre-Installation Inspection and Site Preparation

Before positioning PTFE sliding bearings on substructure support blocks, engineering teams must verify that concrete pedestals meet specified elevation tolerances, flatness criteria, and compressive strength requirements. Cleanliness is paramount; all debris, oil, moisture, or curing compounds must be removed from the masonry plate seating interface. Surveyors should cross-check anchor bolt locations, embedment depths, and projection heights against approved installation drawings. Furthermore, handlers must inspect the sliding interface, stainless steel sheet, and PTFE sheet for any transit damage, scoring, or particulate contamination. Final bearing selection and placement procedures must strictly adhere to approved project design actions, drawings, and governing specifications.

Correct Orientation and Alignment Protocols

Ensuring precise alignment during installation is critical for accommodating thermal expansion and rotational movements in structural bridge systems. Technicians must align the longitudinal and transverse axes of the PTFE sliding bearing with the primary movement vectors indicated in the structural layout drawings. Ambient temperature at the time of installation directly affects the initial offset setting of guided sliding elements; erectors must adjust piston or slider positions relative to baseline thermal correction tables. Misalignment between upper and lower components can induce eccentric loading or edge pinching on the sliding surface. All orientation adjustments must be verified against approved project design actions, drawings, and governing specifications before final load transfer occurs.

For a related project route, review PTFE Sliding Bearings or Pot Bearings in the context of Highway Bridges.

Temporary Locking and Restraint Management

During construction stages such as girder launching, deck casting, or substructure shifting, temporary locking devices are frequently deployed to immobilize sliding bearings. These mechanical restraints prevent uncontrolled displacement or rotation while superstructure loads are applied progressively. Site personnel must ensure that temporary transport clamps or locking plates are installed evenly according to structural sequence requirements. Once structural continuity is established and permanent boundary conditions are activated, these temporary locking mechanisms must be systematically released in accordance with sequential removal protocols. Proper management of restraint systems prevents unexpected stress concentrations and safeguards the sliding interface, always following approved project design actions, drawings, and governing specifications.

Grouting, Load Transfer and Post-Installation Verification

Following mechanical placement and alignment, non-shrink structural grout is typically injected beneath the masonry or base plates to ensure uniform load distribution across the concrete support. Contractors must maintain continuous monitoring during grout curing to prevent voids or settlement beneath the bearing assembly. After grout has attained its specified compressive strength, formwork and temporary shims are removed, allowing dead load to transfer gradually onto the bearing. Engineers should conduct a comprehensive final inspection, measuring gap clearances, horizontal offsets, and sliding surface protection wrappers. All installation milestones, material records, and clearance verifications must be documented in compliance with approved project design actions, drawings, and governing specifications.