Chemical exposure is the most demanding category in rod end corrosion specification. Unlike marine environments where 316 covers most cases, chemical exposure has no single default. The correct grade depends entirely on which chemical, at what concentration, and at what temperature.
Corrosion Data First, Grade Second
Every stainless grade has published corrosion resistance data for common chemicals organized by concentration and temperature. AISI corrosion tables, the ASM Handbook, and manufacturer data (Outokumpu, Sandvik) cover the major grades against hundreds of chemicals. "Stainless steel" is not a chemical resistance claim. It is a starting point for looking up the data.
Common Chemical Environments
Nitric acid (dilute to moderately concentrated, below 60°C): 304 and 316 perform well. Nitric acid is oxidizing and reinforces the passive film on austenitic stainless.
Hydrochloric acid: 304 and 316 are attacked at any concentration. Even trace HCl causes rapid pitting. Nickel alloys (Hastelloy C-276) or higher-alloy duplex grades are required.
Sulfuric acid: highly concentration-dependent. Dilute H2SO4 at room temperature attacks 304 and 316. Concentrated H2SO4 above 93% is handled by 316 at moderate temperatures. A 10% concentration shift can change from acceptable to rapid attack.
Phosphoric acid (food grade): 316 performs adequately. Common in food and beverage processing.
Sodium hypochlorite (bleach, CIP cleaning): 316 is standard for food processing with chlorinated sanitizers. But high-concentration bleach above 100 ppm free chloride in stagnant contact will initiate pitting on 316 at elevated temperatures. Electropolishing and passivation are the mitigation.
The Geometry Problem
Chemicals benign to flat bar stock in corrosion tables may attack crevice geometry in a rod end assembly at lower concentrations. The ball-housing gap, thread roots, and bolt bore all create concentration gradients that produce local conditions more aggressive than the bulk process. Specify electropolishing on all contact surfaces and confirm Critical Crevice Temperature per ASTM G48 Method D for the selected grade.
Beyond the Housing
The PTFE liner is chemically inert to most industrial chemicals. It is rarely the limiting factor. For metal-to-metal rod ends, confirm grease compatibility with the process chemical. Many petroleum-based greases degrade in strong oxidizing acids and chlorinated solvents.