An integrated boiler fuel-train skid bringing fuel conditioning, metering, controlled isolation, ignition supply and utility distribution together on a common structural frame.
The boiler arrangement contains five principal functional circuits: process off gas, natural gas / waste natural gas, igniter gas, nitrogen purge and instrument air. Natural gas and waste natural gas enter through separate inlet legs before joining a common main-burner train. Igniter gas is a branch of the natural-gas supply.
Functional overview only—not a fabrication drawing or an operating sequence. Vents, drains, sensing lines and downstream branches are not counted as separate main trains.
| Circuit | Medium carried | Purpose & arrangement |
|---|---|---|
 01 · Process off gas | Combustible process off gas | Delivers process-derived fuel to the boiler burners. Gas composition and operating conditions are defined by the project process basis. |
 02 · Main NG / WNG train | Natural gas and waste natural gas | Two separately conditioned / metered incoming fuel lines converge into a common main-burner supply train. |
 03 · Igniter gas | Natural gas | A dedicated small-bore ignition-fuel train supplied from a natural-gas branch, feeding the burner igniters. |
 04 · Nitrogen purge | Nitrogen | Provides the purge connection into the process-off-gas piping; it is an auxiliary utility, not a fuel stream. |
 05 · Instrument air | Instrument air | Distributes regulated air to pneumatic valve actuators and the flame-scanner air connections shown in the P&ID. |
Counting basis: three main fuel trains plus two auxiliary utility circuits. This describes system functions, not the number of individual pipe pieces or all physical inlet and outlet connections.
The supply boundary combines piping, structural steel, valves and instrumentation, electrical interfaces and factory verification. The following groups summarize the documented scope rather than reproduce a component-by-component bill of materials.
Translate approved P&IDs, equipment data and general arrangements into fabrication details and shop drawings. Coordinate pipe supports, access, structural interfaces, instrument tubing, cable routing and plant tie-ins, supported by an agreed inspection and test plan.
Provide and assemble process piping, fittings and connections on a steel base frame with pipe supports, lifting provisions and grounding points. Material selection, welding and protective coating follow the approved line classes and project specifications.
Integrate fuel conditioning, flow measurement, pressure regulation, control and shutdown functions with instrument-air distribution. Route factory wiring to separate DCS and BMS / SIS junction-box interfaces. Valve and instrument procurement, or installation of customer-supplied items, follows the awarded scope.
Complete approved material and weld verification, dimensional inspection, pressure testing and assembly checks. Deliver the manufacturing quality dossier, identification, preservation and shipping preparation, with technical site support as agreed.
The requisition and drawings reference international and Chinese requirements for piping, structural fabrication, welding, hazardous-area equipment and enclosure protection. Mandatory local requirements and the contract design basis govern applicability.
| Discipline | Recorded references | Application |
|---|---|---|
| Process piping | ANSI / ASME B31.3; GB/T 20801 | Process-piping design and fabrication, with Chinese pressure-piping requirements and applicable permits / stamps. Individual piping details also reference GB/T 20801 inspection provisions. |
| Structural steel & welding | AISC; AWS; JB/T 1613 | Structural fabrication and applicable project welding requirements. Specific acceptance criteria follow approved drawings and procedures. |
| Welding qualification | ASME Section IX | Welding procedures and personnel qualification as referenced in the inspection and test requirements. |
| Hazardous-area equipment | GB 3836; Zone 2, Group IIC, T4 | Electrical and instrument suitability for the area classification recorded in the general-arrangement notes. |
| Enclosure protection | NEMA 4X; IP66 | Enclosure protection requirements stated in the project drawings. |
| Fire & combustion safety | UFC; UL; NFPA | Fire-protection and combustion-safety requirements applied where specified by the project and governing authority. |
| Coating & quality management | JB/T 1615 / SSPC; EN ISO 9001 or equivalent | Project coating / preservation specifications and the quality-system requirement in the requisition; not a claim of product or supplier certification. |
Review shop drawings, material requirements, welding qualifications, weld / NDE maps and the inspection and test plan before production begins.
Maintain material traceability and inspection records, verify dimensions and welding, and check installation against the approved piping and instrument arrangement.
Hydrotest pipe spools and pneumatically test assembled trains as required by the approved ITP. Complete records, identification, preservation and packing for delivery.
Share fuel composition, flow and pressure ranges, burner arrangement, utility conditions, area classification and the required plant control interfaces.
