GNEE Steel Solution For Large Storage Tank Prefabrication Projects

Relying on profound special steel stock, advanced CNC processing equipment and a mature engineering manufacturing system, GNEE Steel – a world-leading provider of steel materials and deep processing services – delivers a full-chain service covering material supply, steel plate pretreatment, CNC cutting, plate rolling, automatic welding and modular prefabrication.

We provide high-quality, short-cycle and cost-effective large steel storage tank engineering solutions for customers in petrochemical, energy storage, sewage treatment, grain and oil, food and other industries.

For a long time, the construction of large storage tanks (500–100,000 m³) has heavily relied on on-site high-altitude work, manual welding and open-air construction, resulting in widely recognized pain points including long construction cycles, unstable quality, high safety risks and high overall costs:

• Long construction cycle: Restricted by weather, site and labor on site; a single 10,000 m³-class storage tank typically takes 3–6 months.
• Difficult quality assurance: High defect rate of manual welding, uneven welds and anticorrosive coatings easily affected by the environment.
• High safety risks: Frequent high-altitude, hot work and cross-operation make safety control extremely challenging.
• High overall costs: Persistently high expenses for on-site management, labor, equipment leasing and material loss.

GNEE Steel large tank prefabrication service adopts a "factory prefabrication + modular assembly" model to fundamentally break through industry bottlenecks.

I. Project Background

• Client: National oil company of a Middle Eastern country
• Project location: Petrochemical base along the Persian Gulf, Middle East
• Project requirement: Construction of 5 new 10,000 m³ atmospheric crude oil storage tanks for transit storage of export crude oil

Core challenges:

• Strict anti-corrosion requirements due to local high temperature, high salinity and strong sandstorm corrosion environment
• Tight project schedule required by the owner: completion of all prefabrication + on-site assembly within 120 days
• Full compliance with API 650 7th Edition, AWS D1.1 welding standards and local SASO certification mandatory
• High seismic and wind resistance requirements for the coastal tank farm (wind speed 140 km/h, seismic intensity 8 degrees)

II. Product Specifications and Core Parameters

• Tank type: Vertical cylindrical, dome-roof, atmospheric storage tank (API 650)
• Single tank volume: 10,000 m³
• Tank dimensions:
• Diameter: 28.0 m
• Shell height: 16.5 m
• Total height (including dome roof): 18.2 m

Material system:

• Shell plate: Q355R / ASTM A516 Gr.65
• Bottom plate: Q245R / ASTM A283 Gr.D
• Dome roof plate: Q235B
• Accessory flanges: 16MnⅡ

Steel plate thickness distribution:

• Bottom shell ring: 22 mm
• 2nd shell ring: 18 mm
• 3rd shell ring: 14 mm
• 4th shell ring: 12 mm
• 5th shell ring: 10 mm
• Tank bottom middle plate: 10 mm
• edge annular plate: 16 mm
• Dome roof plate: 6 mm

Design parameters:

• Design pressure: Atmospheric pressure (-0.5 kPa ~ +1.5 kPa)
• Design temperature: -10℃ ~ +80℃
• Corrosion allowance: 2 mm inside the tank / 3 mm outside the tank
• Weld inspection: 100% RT for longitudinal seams, 20% RT for circumferential seams, 100% MT for fillet welds

Anticorrosive system:

• Internal surface: Sandblasting Sa2.5 → Epoxy zinc-rich primer → Epoxy glass flake anticorrosive paint
• External surface: Sandblasting Sa2.5 → Epoxy zinc-rich primer → Polyurethane weather-resistant topcoat (UV-resistant & salt-spray resistant)

III. GNEE Steel Solution and Implementation

Special Material Supply

Customized 1,860 tons of special tank steel plates, all with material certificates and UT inspection reports

Spectral analysis and mechanical property re-inspection performed sheet by sheet to ensure compliance with API 650 material requirements

Factory Prefabrication

• Steel plate pretreatment: Automatic leveling → Sandblasting (Sa2.5) → Shop primer coating
• CNC cutting: Fine plasma/flame cutting with blanking precision ±0.5 mm, automatic beveling
• Plate rolling: Arc plates rolled by 4-roll plate bending machine, ovality controlled ≤3 mm
• Intelligent welding: Submerged arc welding + GMAW, first-pass weld qualification rate 98.7%
• Modular pre-assembly: Each shell ring divided into 6 prefabricated modules, max. single module weight 12.8 tons, overall factory assembly and verification

Quality Control

Implementation of 16 quality inspection procedures, complete WPS/PQR welding procedure qualifications

Provision of full documentation package: material certificates, NDT reports, hydrostatic test records, as-built drawings, SASO compliance certificates

Delivery Results

• Full module prefabrication of 5 tanks completed in only 78 days (12 days ahead of schedule)
• Overall construction period 110 days, 10 days ahead of owner's requirement
• One-time qualification in hydrostatic test, settlement observation and air tightness test

IV. Customer Value

• 40% shorter construction period: 6–8 months for traditional on-site construction vs. 110-day delivery for this project
• Significantly improved quality: Factory automated welding, RT first-pass qualification rate 98.7%, far exceeding industry average
• Extended anticorrosion service life: Dust-free shop coating, adhesion ≥8 MPa, designed anticorrosion life over 15 years
• 22% lower cost: Improved material utilization, substantial reduction in labor and management expenses

1. Special Material Supply

High-quality steel sources adaptable to all tank scenarios

• Special materials: Q245R, Q355R, 16MnR, NM360/NM400 (wear-resistant tanks), 304/316L (stainless steel tanks), 9Ni steel (cryogenic LNG tanks)
• Size range: Thickness 5–120 mm, width 1500–2500 mm, length 6–12 m (coiled or flat plates)
• Quality assurance: Full coverage of original material certificates, ultrasonic testing (UT), radiographic testing (RT) and impact tests

2. Steel Plate Pretreatment

High-standard surface treatment and anticorrosive priming

• Process: Automatic leveling → Sandblasting (Sa2.5) → Epoxy zinc-rich primer / inorganic zinc-rich coating
• Advantage: Dust-free workshop operation improves anticorrosive adhesion by 300% and eliminates on-site corrosion risks

3. High-Precision Component Prefabrication

CNC processing + intelligent forming

• CNC cutting: Laser/plasma/flame cutting, blanking precision ±0.5 mm, supporting special shapes, bevels and openings
• Plate rolling: Large 4-roll bending machine for precise shell arc forming, ovality ≤3 mm
• Automatic welding: Submerged arc welding, GMAW, 100% UT/MT/RT weld inspection, Grade I qualification
• Modular prefabrication: Factory pre-assembly of tank bottom middle plates, shell rings, dome/grid shells and accessories (flanges, nozzles, ladders)

4. Full-Process Quality Control

12 key quality control points

• Material acceptance → Layout and lofting → Cutting and blanking → Edge processing → Roll forming
• Assembly and welding → NDT → Dimensional verification → Anticorrosive coating → Marking and coding
• Packaging and protection → Factory acceptance

5. Engineering Services

Full-cycle support from factory to site

• Technical support: BIM modeling, layout optimization, welding procedure qualifications (WPS/PQR)
• Logistics: Heavy cargo transportation, module protection, global port delivery
• On-site guidance: Professional resident engineers for hoisting, assembly, welding, pressure testing and acceptance

Over 50% shorter construction period

Factory prefabrication unaffected by weather with parallel operations; only module splicing required on site. Main structure installation of 10,000 m³ tank completed within 20 days.

Superior quality

Constant temperature and humidity workshop with automated welding, first-pass weld qualification rate ≥98%. Dimensional accuracy and anticorrosion quality far exceed on-site construction.

Enhanced safety control

90% of high-altitude work converted to ground workshop operation, greatly reducing safety risks.

15–30% lower overall costHigher material utilization, reduced labor/management/equipment expenses, and near-zero rework rate.

Complete compliance and certification

Strictly follows international and national standards including API 650, GB 50128, GB 50341, with a full set of as-built documentation provided.

With the integrated capabilities of material + processing + engineering, GNEE Steel has successfully served dozens of large tank prefabrication projects at home and abroad. Its efficient, high-quality, safe and economical delivery has won high recognition from CNPC, CNOOC, Sinochem and overseas large engineering companies.

Going forward, GNEE Steel will continue to deepen storage tank prefabrication technology, promote intelligent, modular and green manufacturing, and provide more reliable steel storage tank solutions for global energy and infrastructure construction. We help customers achieve early project commissioning, early returns and long-term stable operation.

GNEE Steel is a global supplier and deep processing enterprise specializing in high-performance steel plates, pressure vessel steel, wear-resistant steel, weathering steel and stainless steel. It integrates trading, processing, distribution and engineering technical services.

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The company owns large modern processing bases equipped with full-process equipment including CNC cutting, plate rolling, welding and pretreatment, with an annual tank prefabrication capacity of over 50,000 tons. Its products and services cover more than 80 countries and regions, committed to becoming a trusted one-stop partner of steel materials and engineering manufacturing for global customers.