Diesel Sample Collection Process from Storage Tank by SGS
The process for collecting diesel samples from storage tanks by SGS (a global inspection, testing, and certification company) typically follows industry standards such as ASTM D4057 (Standard Practice for Manual Sampling of Petroleum and Petroleum Products) or equivalent protocols like ISO 3170, ensuring accuracy, safety, and chain of custody. While SGS does not publicly detail proprietary step-by-step procedures in all cases, their services involve trained inspectors using specialized equipment to collect representative samples for quality testing (e.g., for contaminants, water, sediment, density, sulfur content, and biodiesel blends). Based on standard practices they adhere to and descriptions from their services, here’s how the collection generally works:
Sample Collection Process
- Preparation and Site Assessment:
- SGS inspectors arrive at the site (e.g., refinery, storage facility, or terminal) and notify the tank owner or operator. They verify tank labeling, access points, and safety conditions.
- Personal protective equipment (PPE) is worn, including gloves, safety glasses, high-visibility clothing, and sometimes respirators. Static electricity is grounded by touching a metal part of the tank away from the sampling point.
- The tank is inspected for integrity, and measurements like fuel depth are taken using a gauge stick (non-sparking material, marked in millimeters) to determine sampling levels.
- Spill containment measures, such as absorbent pads, are placed around the access port.
- Sampling Methods:
- Samples are collected from various levels to ensure representation: upper (top), middle, lower (bottom), or all-level (composite) samples. For diesel, bottom samples are common to detect water, sediment, or microbial contamination.
- Equipment Used:
- Weighted bottle sampler: For upper, middle, or all-level samples. A bottle attached to a cord is lowered to the desired depth, filled by pulling a stopper, and retrieved.
- Submerged sampler (e.g., Bacon Bomb or thief sampler): Ideal for bottom samples. A plunger-valve device is lowered to the tank bottom, filled, and sealed upon retrieval.
- Plastic or metal tube samplers: For simpler dips, where the tube is inserted, filled, and transferred to a container.
- The sampler is slowly lowered to avoid agitation, filled completely (until bubbles stop), and retrieved carefully. Excess fuel is disposed of safely.
- For underground storage tanks (USTs), access is via fill ports or monitoring wells; for aboveground storage tanks (ASTs), it’s through hatches or gauges.
- Water detection may involve applying water-finding paste to the gauge stick, dipping it to the bottom, and checking for color changes indicating free water (removed if exceeding limits, e.g., 25 mm for diesel).
- Samples are transferred to clean, vapor-tight containers (e.g., glass bottles or metal cans, typically 1 liter capacity) filled to about 80% to allow for expansion.
- Frequency: Often periodic (e.g., monthly) for ongoing monitoring, or on-demand for trades, with bottom samples emphasized for FAME-blended diesel to check for microbiological issues.
- Sealing and Labeling:
- Immediately after collection, containers are capped tightly and secured with tamper-evident seals (e.g., numbered security seals) to maintain chain of custody.
- Labels include details like sample ID, date/time, tank number, sample type (e.g., bottom or composite), location, and inspector’s name.
- Samples are placed in secure transport carriers and sent to an SGS lab for analysis (e.g., under standards like ASTM D975 for diesel quality).
- Safety and Compliance:
- Non-sparking tools are used to prevent ignition. Spills are contained, and excess fuel is handled as hazardous waste.
- The process complies with environmental regulations to avoid contamination, and a visual check for clarity/brightness is done on-site (e.g., per ASTM D4176).
SGS offers these as part of their diesel fuel testing, petroleum product analysis, and tank inspection services, available 24/7 at key locations.
Mention of Seal Number and Tank Number in the Report
SGS reports (e.g., Quality & Quantity or Certificate of Analysis) are structured documents that include sections like summaries, time logs, analysis results, measurements, and sample details. They explicitly reference seal numbers and tank numbers to ensure traceability and verify the sample’s origin:
- Tank Number: Listed in sections like “Sample Source,” “Shore Measurement,” or “Tank Data.” It identifies the specific storage tank (e.g., “Shore Tank 25” or “Tank: 24”) from which the sample was drawn, along with details like gauge soundings, volume, temperature, and observed discrepancies. For example, in a shore tank measurement: “Tank: 24 Open Gauge Sounding mm 8,133, TOV: Litres 44,562,602.”
- Seal Number: Mentioned in “Sample Report,” “Distribution,” or “Analysis Report” sections to confirm sample integrity. It’s tied to the container or sample ID (e.g., “Seal No.: SGS-123456” or “Seal No. Distribution: 26-Oct-2016”). This verifies that the sample was not tampered with from collection to lab analysis. For instance: “Sample No: SGS, Sample Source: Ships Tanks, Source ID: 1-6 P/S and Sl P/S, Seal No.: [specific number].”
Reports may also include photos, discrepancies (e.g., water content), and certifications. Clients receive these for compliance, trading, or regulatory purposes.
