DISCUS Engineered Products

Trust your inner roof

DISCUS Technical Bulletins

Oct 6

Written by:
David Rosenkrantz and Julie Anne Cormier

Posted in:
Internal Floating Tank Covers,


3 things you should know before you close the hatch

manway0071-400x298DISCUS full contact aluminum internal floating covers feature a combined manway/PV vent. This reduces the number of emission sources as compared to covers with separate manways and vents.

Some companies provide their version of a similar combination,

however … DISCUS is the only company that provides a true, single emission equivalent manway/vent combination.

While working on a project this month down in Corpus Christi, Texas, a customer brought us a problem they were having with another company’s combination manway: their environmental group was rejecting the single emission source claim made by the other vendor. They wanted to know how DISCUS could do better. The answers are in our standard manway and vent designs.


  1. DISCUS uses a true bolted and gasketed manway as opposed to others who use a hinged design with one or two bolts or latches. They may meet the letter of the rule with a design that includes “bolts”, however it may not meet the intent of the rule or visually demonstrate equivalency to the type of manway used to develop the emission factors.
  2. DISCUS manways are gasketed and secured all around with closely spaced stainless steel bolts. Our PV vents include a weighted, gasketed cover similar to those found on steel floating roofs (again similar to the device used to establish emission rates) and do not suffer the appearance or functional inadequacies of the older or flapper-door styles.


  3. Beyond emission concerns, we always look at the safety aspects of every piece of equipment on or associated with our cover. Having seen manways with ladders positioned in very unsafe ways, we created a safe and permanent way to gain access through our floating covers. Every DISCUS cover manway includes an attached OSHA 300-pound-rated ladder for safe access, used by our installation crew and then secured to the cover for future access, inspections, etc.

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