Case Study: Closed Loop Sampling System Upgrade at a Sinopec Refinery

Project Overview

As one of the largest integrated energy and chemical companies in the world, Sinopec operates dozens of refineries and petrochemical complexes across China. At a major refinery in eastern China, the facility management identified a systematic gap in their process sampling infrastructure: multiple distillation units and intermediate tank farms were still relying on traditional open-loop (grab) sampling methods that posed significant safety, environmental, and data-quality risks.

Wanan Technology was contracted to design, manufacture, and supply a comprehensive closed loop sampling system package covering 18 sampling points across three process units — crude distillation, catalytic cracking, and product finishing. The project scope included engineering design, material selection, fabrication, factory acceptance testing (FAT), and on-site commissioning support.

The Challenge: Aging Sampling Infrastructure

The refinery’s existing sampling setup consisted of simple needle valves and open bottles — a method that had been in use since the facility’s original construction. Over years of operation and multiple HSE audits, several critical issues had been documented:

• Operator Exposure: Sampling personnel were routinely exposed to benzene-containing streams, hydrogen sulfide (H2S), and volatile hydrocarbon vapors. Despite PPE requirements, the risk of acute exposure during high-pressure sampling events remained a persistent concern for the HSE department.
• Fugitive VOC Emissions: Each open-loop sampling event released an estimated 0.5 to 2 liters of hydrocarbon vapor into the atmosphere. With hundreds of sampling operations per week across the refinery, the cumulative emissions were flagged in the facility’s environmental compliance audit as a priority remediation item.
• Sample Inaccuracy: Lab personnel reported inconsistent Reid Vapor Pressure (RVP) results and variable distillation endpoints on identical feedstock samples. Root cause analysis traced the discrepancy to light-end losses during open-air sample transfer — particularly problematic for naphtha and gasoline blend stock analysis.
• Regulatory Pressure: China’s evolving GB 31570-2015 standard for petroleum refining pollutant emission limits, combined with Sinopec’s internal corporate HSE upgrade program, created a firm deadline for sampling system modernization.

Solution Design & Engineering

Wanan’s engineering team conducted a site survey to map all 18 sampling points, documenting process conditions for each location:

Based on this survey, three sampling panel configurations were designed:

1. Constant-Pressure Piston Cylinder Panels (8 points)

For volatile streams (naphtha, LPG, gasoline, reformate), constant-pressure sampling cylinders with spring-loaded pistons were specified. These maintain the sample at process pressure throughout extraction and transport, preventing light-end flash vaporization that would corrupt RVP and distillation analysis. The panels were equipped with dual-valve isolation, pressure gauges, and integrated purge loops.

2. Standard Cylinder Sampling Panels (7 points)

For stable liquid streams (diesel, kerosene, atmospheric residue, LCO), standard 316L stainless steel sampling cylinders with needle valves were selected. These panels included a process isolation valve, purge/vent valve, and cylinder connection with quick-connect fittings for efficient operator workflow.

3. Heated Sampling Panel (3 points)

For high-viscosity streams (atmospheric residue at 350 C), steam-traced heated panels with oversized bore tubing (3/8 inch minimum) were engineered to maintain fluidity during the sampling cycle. The panel design included a cooling section to bring the sample to a manageable temperature before entering the cylinder.

Equipment Supplied

Implementation & Commissioning

The project was executed over a 14-week timeline:

1. Weeks 1-3: Detailed engineering, P&ID review, and material take-off. Wanan engineers worked with the refinery’s process engineering department to confirm all tie-in points, isolation valve locations, and sample routing paths.
2. Weeks 4-10: Manufacturing and fabrication at Wanan’s ASME U-stamp certified facility in Honghu, Hubei. All pressure-bearing components were hydrostatically tested at 1.5x design pressure. Material traceability per EN 10204 3.1 was maintained throughout.
3. Weeks 8-9: Factory Acceptance Testing (FAT) conducted at Wanan’s facility with Sinopec inspection engineers present. Testing included pressure hold tests, valve functional tests, cylinder leak tests (helium sniffer at 1×10-6 std cc/sec sensitivity), and dimensional verification.
4. Weeks 11-13: Shipment, site installation, and mechanical completion. Wanan field service engineers supervised the installation of all 18 sampling panels, including process tie-ins, tubing runs, and structural supports.
5. Week 14: Commissioning and operator training. Each sampling point was functionally tested with actual process fluid. Operators received hands-on training on purge procedures, cylinder handling, and maintenance protocols. A detailed operation & maintenance manual (in Chinese and English) was delivered.

Results & Outcomes

Post-installation performance was monitored over a 6-month period, with the following documented outcomes:

Beyond the quantifiable metrics, the refinery’s HSE department reported that the closed loop sampling upgrade was cited positively in their subsequent corporate safety audit. The environmental compliance team confirmed that sampling-related fugitive emissions were effectively eliminated from the facility’s emissions inventory report.

Key Takeaways for Refinery Operators

This project illustrates several principles that apply broadly to sampling system upgrades at any refinery or petrochemical facility:

• One size does not fit all. A single sampling panel design cannot serve all process conditions. Volatile streams require constant-pressure piston cylinders; viscous streams need heated panels; stable liquids can use standard configurations. Proper engineering per point is essential.
• Material traceability matters. For refinery applications, 316L stainless steel with full EN 10204 3.1 certification is the minimum standard. Sour service (H2S-containing) requires NACE MR0175/ISO 15156 compliance. Skipping material documentation to save cost is a false economy.
• Operator training is non-negotiable. Even the best-designed closed loop system will underperform if operators fall back on old habits. Structured hands-on training during commissioning, supplemented by clear visual procedures at each sampling point, ensures sustained proper use.
• Spare parts planning prevents downtime. Seals, gaskets, and spare cylinders should be ordered with the initial equipment. A 2-year spare parts inventory was included in this project and proved essential when one cylinder needed re-testing after a sour service exposure event.

For facilities planning similar upgrades, Wanan Technology offers site survey, engineering design, and custom manufacturing of closed loop sampling systems compliant with ASME, GB, ATEX, and PED standards. Our experience spans 40+ countries and includes work for Sinopec, PetroChina, ExxonMobil, Lukoil, and BASF facilities.

Frequently Asked Questions

Planning a sampling system upgrade? Wanan Technology’s engineering team can help you assess your facility’s needs, design custom solutions, and deliver ASME-certified equipment with full documentation. We have supplied systems to refineries and chemical plants across 40+ countries.

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