Knock-out drums in the nature of metal tanks for separating gas from liquid being parts of oil and gas midstream processing machines; Flash tanks in the nature of metal tanks for separating gas from liquid being parts of oil and gas midstream processing machines; Separators in the nature of metal pressure vessels used to separate oil from gas being parts of oil and gas midstream processing machines; Slug catchers in the nature of metal containers for use in storing gas or liquid being parts o...