Polyester slings are unsuitable around which substances?

• A. Aldehydes and Ethers
• B. Concentrated Alkalis and Sulfuric Acids
• C. Water and Oxygen
• D. Oils and Solvents

Answer: (B)

Polyester slings have good strength and resist many chemicals, but they are not tolerant of strong bases and strong mineral acids. Concentrated alkalis and sulfuric acid attack the ester bonds in polyester fibers, causing hydrolysis and degradation that weaken the sling and can lead to failure under load. That makes these substances the ones to avoid with polyester slings. In contrast, water, oxygen, and many oils or common solvents typically don’t cause rapid deterioration, though it’s always wise to check chemical compatibility for any exposure.