Mechanical seals fail for the same basic reasons everywhere: heat, dry running, contamination, misalignment and the wrong materials for the job. But the Bay Area puts its own spin on those causes. Refineries along the Carquinez Strait answer to the Air District’s equipment leak rules, wastewater plants fight a steady stream of wipes and grit, heat waves push inland temperatures past 110°F, and wine country runs its pumps hard every fall. Here are the mechanical seal failures that show up most often in Bay Area plants, and what you can do about each one.
1. Small Seal Leaks Become Compliance Problems at Refineries and Chemical Plants
At refineries and chemical plants in Richmond, Rodeo, Martinez and Benicia, a weeping pump seal isn’t only a maintenance issue. The Bay Area Air Quality Management District’s Regulation 8, Rule 18 (Equipment Leaks) sets leak limits and repair timelines for pumps, compressors, valves and other components. Amendments adopted on September 4, 2024 extend leak detection and repair requirements to more equipment in heavy liquid service, including certain pumps.
That means a seal that “only drips a little” can trigger inspection findings and forced repair deadlines. Common root causes behind these leaks include worn or heat-checked seal faces, hardened O-rings and seals running outside the conditions they were designed for.
How to prevent it: track seal leakage as a reliability metric, not just an emissions number. Repair seals at the first sign of leakage, and for volatile services, talk to a seal specialist about dual seals or seal support systems. Our post on pump seal support systems covers the basics.
2. Process Changes at Converted Refineries Expose Seal Materials
Two of the region’s refineries have been approved for conversion to renewable fuels. Contra Costa County approved permits for Phillips 66 to convert its Rodeo refinery and for Marathon to convert its Martinez refinery to renewable diesel production, as Argus reported. When the fluid in a pump changes, the seal that worked for years may not be the right seal anymore.
Elastomers are a good example. A U.S. Department of Energy renewable diesel overview notes that fuels need a minimum level of aromatics for elastomer swell to ensure sealing. Low-aromatic fuels can let O-rings and other secondary seals shrink and leak, even when the seal faces are in good shape.
How to prevent it: any time the service changes, whether it’s a new feedstock, a new temperature range or a new cleaning chemical, review the seal’s face materials and elastomers before the first leak tells you something is wrong. Our guide to selecting the correct pump seal walks through what to check.
3. Heat Waves Lead to Flashing and Dry Running
Inland Bay Area heat can be extreme. During the September 2022 heat wave, Livermore reached 116°F and San Jose set an all-time high of 109°F, according to ABC7 News. The heat strained plant equipment, too: at a Crockett wastewater plant, the operator reported that blowers overheated during the record-breaking heat wave.
Mechanical seals depend on a thin film of liquid between the faces. When process temperatures climb, that film can flash to vapor, leaving the faces to run dry. The result is heat checking (fine cracks across the face), blistering of carbon faces and cooked elastomers. Low tank levels, closed suction valves and vapor lock cause the same damage.
How to prevent it: make sure flush and cooling plans are working before summer, watch suction conditions and tank levels, and never run a mechanically sealed pump dry, even for a few seconds.
4. Wipes, Rags and Grit Destroy Seals in Wastewater Service
Bay Area wastewater agencies have been fighting “flushable” wipes for years. ABC7 reported that EBMUD workers have had to shut down equipment and clean out debris by hand, and most of what they pull out is wipes. EBMUD has noted that it can take up to two weeks to clear wipes from its equipment, and Central San has run a long-standing public campaign against flushing them.
For pump seals, ragging is a double hit. Wipes that wrap around an impeller unbalance the rotating assembly, which increases vibration and shaft deflection and lets the seal faces open and close. Meanwhile, sand and grit work their way between the faces and wear them down.
How to prevent it: use hard face combinations such as silicon carbide or tungsten carbide in abrasive service, keep screens and grinders maintained, and consider a clean flush to keep solids away from the faces. For more on lift station reliability, see our water and wastewater page.
5. Sugar, Product Buildup and Cleaning Chemicals in Food and Wine
From late summer into fall, wineries in Napa, Sonoma and the surrounding valleys run must, juice and wine pumps through long harvest shifts. Sugary and sticky products can dry and crystallize on seal faces when a pump sits idle, then tear the faces apart on the next startup. Aggressive clean-in-place (CIP) chemicals cause a different problem: elastomers that aren’t compatible with the cleaning solution swell, crack or harden.
How to prevent it: flush pumps before shutdown, consider a quench on sticky services, and confirm that elastomers are compatible with both the product and the cleaning chemicals. Learn more about our pump solutions for wineries and food processing.
6. Misalignment, Vibration and Running Off the Best Efficiency Point
Not every seal failure is caused by the seal. Shaft misalignment, worn bearings, cavitation and operating a pump far from its best efficiency point all create shaft movement that the seal has to absorb. As John Crane explains in its overview of the causes and corrective procedures for seal leakage, finding the real cause of a leak means looking at the whole system, not just the seal that failed.
How to prevent it: align pumps precisely after installation and after any motor or pump work. Our laser pump alignment service helps here. Also check vibration trends, and size pumps so they run near their best efficiency point. Our post on how cavitation damages pumps explains one of the most common hidden causes.
A failed seal is evidence. The wear on the faces usually points straight to the root cause.
Repair the Seal, Then Fix the Cause
Before you order a replacement, have the old seal inspected. The wear pattern on the faces, the condition of the elastomers and the state of the springs usually point to the root cause, and many seals can be reconditioned for less than the cost of a new one.
DXP Pacific’s Richmond service shop provides mechanical seal repair for customers across the Bay Area, Northern California and Nevada. The shop repairs cartridge and component seals, including John Crane and Flowserve, checks rebuilt cartridge seals on its new test bench and quotes every repair against the price of a new seal before work starts. Send us photos of your seal and nameplate, or call (510) 236-5481 to talk with our Richmond team.