Column-type pressure vessels still fall under the category of pressure vessels. Structurally, they can be regarded as piston accumulators without pistons; their internal wall‑surface finish differs from that of piston accumulators. It is sufficient to ensure cleanliness and to meet the surface roughness requirements that accommodate gas‑induced expansion and cyclic stress. The primary consideration in selecting column‑type cylinders is installation convenience, though their cost is higher than that of standard pressure vessels.
