Does the bladder seal commonly used in storage tanks currently meet the requirements of GB 31571-2015?
Thread Content
GB 31571-2015 requires that for internal floating roof tanks, efficient sealing methods such as liquid-filled sealing, mechanical shoe-type sealing, and double-sealing should be used. Does the commonly used bladder sealing for storage tanks meet the requirements of GB 31571-2015?
Sack-type sealing is a relatively new method for tank sealing, characterized by advantages such as simple sealing setup, easy operation, and good sealing performance. However, according to the provisions of GB 31571-2015, internal floating roof tanks should employ efficient sealing methods such as liquid-settling type, mechanical shoe type, and double-seal systems; bladder seals are not explicitly mentioned or recommended. Therefore, from a standard perspective, bladder seals do not meet the requirements of GB 31571-2015. It should be noted, however, that bag seals also have their advantages and suitable applications in practical use; whether their use is appropriate depends on a comprehensive consideration of various factors such as the material of the storage tank, the substance being stored, and the operational requirements. .
It does not meet current standards, and the storage tank requires modification, including changes to the type of floating deck and the sealing method.
It can’t be said to not meet the requirements just because it isn’t mentioned; according to the interpretation of API650, a pouch seal belongs to the liquid-set type.
The bladder seal has two disadvantages: the bladder is typically filled with materials such as polyurethane, and when it is damaged, the liquid phase will enter the bladder seal, causing the bladder to absorb this liquid phase and thereby affecting the sealing performance； The filling material for the sac works well in the initial stage of use, but as it ages and deforms over time, it results in poor sealing, thereby affecting the sealing performance ； Therefore, pouch seals do not belong to high-efficiency seals.
Thank you for the reply. Do relevant standards state that bag seals do not belong to the category of high-efficiency seals?
There shouldn’t be any; such a standard won’t be established. If there are technological advancements and new materials for bag-type seals are developed, the sealing performance will improve. Not everything can be judged in a blanket manner.