If it’s been a considerable time since the topic of grab sampling—you may also know it as "closed-loop sampling", "spot sampling" or "lab sampling"—has landed on your desktop and you’re now considering new installations or upgrades, a brief review of current grab sampling systems’ advantages and disadvantages can help guide your decision-making process. In contrast to systems installed a decade or more ago, modern sampling systems offer better ergonomic design and new capabilities that improve sampling safety, efficiency, and accuracy.

Petrochemical plants concerned with meeting California Division of Occupational Safety and Health (Cal/OSHA) requirements and stricter Bay Area Air Quality Management District (BAAQMD) environmental regulations associated with sour crude, gas and gas condensate, and refined liquid processing can further benefit from newer designs and functionality. Below, we summarize key grab sampling systems’ advantages and disadvantages to look for when installing or upgrading a system in a strict regulatory environment like California.

Consider These Grab Sampling Systems’ Advantages

Modern grab sampling systems are designed, configured, and assembled to overcome the limitations associated with earlier grab sampling designs. Many older systems did not have ergonomics and safety at the forefront of their design. As such, they may have been installed in locations with poor access for workers or away from critical resources like drains, making it more difficult to get a representative sample.

When planning new installations or upgrades for existing sampling processes, look for these improvements/features that facilitate safer, more efficient, and consistent sampling.

• Optimized sampling processes incorporate ergonometric panel designs with sequencing steps to simplify sampling and reduce the possibility of operator errors leading to potential Cal/OSHA sanctions
• More instrumentation including pressure and temperature gauges, meters, and flow indicators to monitor sampling environments and ensure samples are taken under the right conditions for better quality assurance
• Less dead space that causes fluid from an earlier sample to leak into a new sample and compromise sample quality
• Zero flushing time to keep transport lines fresh and ready to capture samples for better operational efficiency
• Tube fittings that eliminate the potential leak points associated with threaded connections and reduce the risk of compromised sample quality, reducing fugitive emissions and the potential for BAAQMD sanctions
• Rupture discs or relief valves prevent sample cylinder overpressure from temperature changes or overfilling in line with AMSE codes, decreasing the possibility of fines by Cal/OSHA

When you’re considering new installations or upgrades to existing systems, you should consult with a grab sampling vendor with proven expertise in addressing the unique needs of the local petrochemical plants. Experienced technicians have a detailed knowledge of BAAQMD and Cal/OSHA regulations. They can work closely with you to customize closed-loop systems, incorporating many of the capabilities mentioned above, as well as making additional configuration recommendations to meet your specific requirements. As a result, greater sampling efficiency, increased consistency in sampling quality, and safer operations—clear advantages for plants with critical sampling requirements.

Caveat: Potential Disadvantages

In my years of working directly with a wide range of Bay Area petroleum and chemical plants that have installed new or updated grab sampling systems I have found that, truthfully, it’s difficult to find any disadvantages in a well-designed system. However, a few caveats are worth mentioning to set realistic expectations.

Depending on the type of fluids being processed—particularly those emitting VOCs—and current BAAQMD regulations, you may find that enclosures, eductors to remove toxic fumes, return to flare piping, eye wash, or safety shower are required. These add to design, installation, and ongoing maintenance costs. If your project involves retrofitting a replacement or upgrading components, some additional design and fabrication may be required to accommodate existing physical or infrastructure limitations.

While these caveats may initially appear to be disadvantages from a design and cost perspective, especially if you are contemplating dozens of sampling system replacements or upgrades, many of these are regulatory requirements. And, in the long run, these “disadvantages” promote better efficiency, quality, and safety for your grab sampling processes. Again, a leading grab sampling vendor should be able to help identify where the benefits outweigh the costs and how to manage the overhaul. 

Local Expertise For Installing or Upgrading Grab Sampling Systems

Whether you’re faced with the need to install grab sampling systems to support a new process, retrofit new stations for an existing process, or upgrade components of a current system, it’s best to work with local, factory-certified experts. With proven industry experience, they’ll help you to assess grab sampling systems’ advantages and disadvantages of the various design options. Based on the assessment, they’ll then design, configure, and assemble the systems to meet your specific plant application needs. 

You’ll benefit from ergonomic designs and facilitate safe and efficient sampling, standardized components that help reduce ongoing maintenance costs, and, most importantly, greater confidence regarding sampling safety, consistency and accuracy. 

To find out how Swagelok Northern California can help you assess grab sampling systems' advantages and disadvantages by providing expert consultation and Assembly Services, contact our team today by calling 510-933-6200!

About Morgan Zealear | Product Engineer, Assembly Services

Morgan holds a Bachelor of Science in mechanical engineering from University of California at Santa Barbara. He is certified in Section IX, Grab Sample Panel Configuration and Mechanical Efficiency Program Specification (API 682), and he is well versed in B31.3 Process Piping Code. Before joining Swagelok Northern, he was a manufacturing engineer at Sierra Instruments, primarily focused on capillary thermal meters for the semiconductor industry (ASML).