Titanium screws, our most corrosion-resistant metal screws, can tolerate chemicals, sea water, and acids. They are roughly 40% lighter than steel screws and have a great strength-to-weight ratio. All of them satisfy the dimensional requirements of ISO 4762 (previously DIN 912) or ASME B18.3. Under the head, the length is measured.
If you are unsure of the threads per inch, go with screws with coarse threads, which are the industry norm.