Large-Scale Special Equipment and Field-Installed Equipment
This domain covers equipment whose final configuration is created on site: field-erected spheres and tanks, site-assembled boilers, long-distance pipelines, and large cranes and rides assembled from shipped sections. The exam tests whether you understand that factory inspection does not travel with the sections.
Why field work is different
Shop conditions - positioners, controlled atmosphere, post-weld heat treatment furnaces - are absent. Site welding introduces wind, humidity, low temperature, restricted access and fit-up stress. Consequently the installation supervisory inspection (安装监督检验) must cover: foundation acceptance and settlement measurement, alignment and plumbness, fit-up and groove preparation, welding procedure qualification coverage for the actual site joints, welder qualification covering method/position/thickness/material, preheat and interpass control, post-weld heat treatment (local or整体), NDT at the specified proportion, and the pressure test.
Specific controls
- Welding stops when wind speed, relative humidity or ambient temperature exceed the procedure's limits.
- Spheres and large tanks usually require overall post-weld heat treatment after all site welds are complete, then hydrostatic test and tightness test.
- Large crane erection adds rail/bogie alignment, structural bolt torque, and load testing: static at 1.25× rated load, dynamic at 1.1×.
- Large equipment lifting schemes above the defined scale require expert review before execution.
Worked example
A 1000 m³ spherical tank is delivered as plates and forged segments and welded on site. Reasoning: the shop pressure test on segments proves nothing about site joints. Verify the welding procedure qualification covers the actual thickness and material, every welder's qualification matches the position used, all site welds are completed before overall heat treatment, hardness and NDT are done after heat treatment, and only then apply the hydrostatic test at 1.25× design pressure with water temperature above the brittle-fracture limit and the foundation monitored for settlement during filling.
Traps that cost marks
Assuming factory supervisory inspection extends to site joints; skipping heat treatment before the pressure test; ignoring foundation settlement during hydrostatic filling; treating bolt torque as a visual item.