API 6D DN15-DN2000 Class 600 Flanged End Gear Operated High‑Pressure Forged Steel Trunnion‑Mounted Fixed Ball Valve

VI. Complete Manufacturing & Quality Control Workflow

TIANYU implements multi‑stage quality gate checkpoints running through raw‑material verification, forging thermal treatment, precision CNC machining, component cleaning, assembly, pressure performance testing, final inspection and document packaging, eliminating latent defects before product shipment.

A. Raw Material Incoming Inspection & Qualification

• All forging blanks are sourced from ISO‑certified forging mills, accompanied by original EN10204 3.1 material test reports covering chemical composition and mechanical‑test records.
• In‑house incoming material verification: XRF spectral analysis validates chemical composition compliance with ASTM specification. Sample tensile test and Charpy impact test verify mechanical‑property indicators.
• Non‑destructive testing for forging blanks: Ultrasonic Testing (UT) detects internal forging discontinuities; Magnetic Particle Inspection (MPI) screens surface cracks. Forging blanks failing NDT screening get rejected and do not enter machining workflow.

B. Hot Forging & Heat‑Treatment Process

• Multi‑direction hot die‑forging forms valve body, bonnet, ball and trunnion blanks. Hot forging breaks cast‑ingot coarse grain structure, achieving dense, uniform metallographic microstructure.
• Strict heat‑treatment execution for A105 forged components: Normalizing plus tempering procedure relieves forging residual stress, optimizes grain structure and stabilizes mechanical performance across component cross‑section. Hardness spot‑check confirms heat‑treatment effectiveness for every production batch.
• Post‑heat‑treatment shot‑blasting removes surface scale, preparing component surface for subsequent overlay welding and machining steps.

C. Precision Machining & Hard‑Facing Overlay

• Five‑axis CNC machine tools execute high‑precision machining for body flange faces, seat‑pocket bores, trunnion bearing pockets and stem passage. Critical coaxiality and flatness tolerances are strictly controlled, guaranteeing assembly fit accuracy.
• Stellite 6 hard‑facing overlay is applied onto ball and seat sealing raceway by plasma transferred‑arc welding process. Welding parameters are locked per qualified welding procedure specification (WPS). Post‑weld non‑destructive liquid penetrant inspection detects overlay welding surface micro‑cracks.
• Grinding and lapping process for ball sealing sphere achieves sphericity tolerance ≤0.02 mm and surface roughness Ra ≤0.4 μm. Seat‑ring sealing face receives matching lapping work to realize high‑quality surface contact between ball and seat‑ring pairs.

D. Ultrasonic Component Cleaning & Mechanical Assembly

• Every single machined component goes through degreasing and ultrasonic cleaning bath to eliminate metal chips, machining oil and particulate contamination. Residual particles on sealing surfaces will cause seat‑leakage risk, so cleaning procedure represents a vital quality control step.
• Assembly proceeds following documented assembly sequence: install trunnion thrust‑bearing sets, insert ball‑trunnion sub‑assembly, fit pre‑spring‑loaded seat‑rings, mount stem assembly, install bonnet‑body spiral‑wound gasket, fasten body‑bonnet studs with cross‑pattern controlled torque, install stem‑packing stack and gland flange, mount worm‑gear manual operator and perform stroke alignment adjustment.
• During assembly phase, inspectors verify every critical fit clearance and bolt torque record.

E. Full‑Sequence Pressure Performance Testing

• Hydrostatic shell test is performed first, pressurizing valve body cavity to 1.5 × rated pressure for minimum 30 minutes. Inspectors check entire body, bonnet and flange joint for sweating, leakage or permanent deformation.
• Bi‑directional hydrostatic seat test: Apply 1.1 × rated pressure to upstream and downstream side in turn, record seat‑leakage situation, comply with ISO 5208 acceptance criteria.
• Functional stroke test: Complete 50 continuous open‑close cycles, validate smooth quarter‑turn rotation, correct gear‑box position‑indicator reading and proper mechanical stop‑limiter function.
• Sample units from each production batch undergo API 607 fire‑safe qualification test periodically for product‑type validation.

F. Final Visual Inspection, Documentation & Export‑Oriented Packaging

• Visual inspection checks exterior paint finish, marking stamp (nominal size, pressure‑class, material grade, TIANYU brand logo, standard marks), flange‑face protection condition.
• Shipment document package includes EN10204 3.1 material certificates, pressure‑test report, dimensional drawing, installation‑maintenance operation manual and CE‑PED declaration of conformity.
• Valves are protected with plastic flange‑end caps, wrapped with moisture‑proof membrane and packed into plywood export crates to avoid mechanical damage and dampness during ocean‑freight long‑distance transportation.

VII. Verified Product Advantages of TIANYU Forged Steel Trunnion‑Mounted Ball Valve

Benefits derive from forged metallurgical quality, trunnion‑supported mechanical architecture, Stellite hard‑overlay sealing and strict full‑process quality management, delivering tangible value for end‑users in capital expenditure, operational safety and total‑life‑cycle cost control.

A. Enhanced Mechanical Reliability Under High‑Pressure Working Circumstance

• Forged raw‑material baseline eliminates casting‑related internal defects, delivering higher resistance to pressure surge and hydraulic shock compared with cast‑body ball valves. Under identical pressure‑class rating, forged construction offers larger safety margin for transient pipeline pressure spike events.
• Trunnion‑anchored ball transfers high‑pressure‑induced hydraulic thrust onto valve‑body bearing structure, preventing excessive seat‑compression load. This greatly reduces seat wear velocity under frequent operation cycles, extending service life in cyclic‑load pipeline service.
• Anti‑blow‑out stem and cavity‑over‑pressure relief mechanism mitigate two major high‑pressure valve failure modes, improving intrinsic equipment safety for unattended‑operation pipeline stations.

B. Stable Sealing Performance Across Wide Working Condition Range

• Spring‑pre‑loaded metal‑hard‑seat configuration provides consistent specific sealing pressure, compensating thermal expansion difference and minor wearing accumulation over long‑term runtime.
• Optional dual‑seal structure combining metal‑hard‑seat plus soft‑insert achieves both Class VI bubble‑tight shut‑off for normal operation and API 607‑compliant metal‑backup‑seal when soft insert fails under fire accident.
• ISO 15848‑1 Class AH stem‑packing configuration restricts fugitive volatile‑medium emission, satisfying environmental‑compliance requirements for refineries and gas‑transmission facilities.

C. Reduced Operation & Life‑Cycle‑Maintenance Expense

• Trunnion design lowers required operating torque, which avoids procurement of oversized expensive actuators for large‑size high‑pressure valve projects. Manual worm‑gear operation becomes feasible for many large‑size high‑pressure working conditions.
• Bolted‑body maintainable construction allows on‑site replacement of wearing parts including seat‑rings and stem‑packing without removing valve from pipeline, cutting plant‑shutdown time and maintenance‑labour cost.
• Full‑port bore design reduces permanent pressure loss across valve, lowering compression‑or‑pumping‑system energy consumption for continuous‑flow industrial pipelines.

D. Global‑Project‑Friendly Standardized Interoperability & Certification Credentials

• Adherence to API 6D, API 608, ASME B16.34, ASME B16.5 and ISO‑series standards guarantees mechanical interchangeability for international EPC engineering projects.
• Complete third‑party‑recognized certifications including CE‑PED, ISO 9001 and material traceability documentation simplify tender‑document review and site‑acceptance‑inspection workflow for global buyers. Multiple end‑connection options and actuation‑mounting interface match diversified‑project‑design requirements.