Pressure Testing: Best Practices

Abstract

Success below the seas comes from careful preparation topside. Pressure testing remains one of the most useful tools designers have available to assure their systems function as intended, whether a company chooses to have in-house pressure test capability or to work with a commercial test facility.Capt. Don Walsh, pilot of the bathyscaph Trieste on its historic two-man dive to the floor of the Challenger Deep in the Mariana Trench, said with a grin, “Successful operations depend upon a Skill-to-Luck ratio. While luck is important, you always want skill to be more than 50%.”Given the limited availability of ship time, the danger to personnel in close quarters onboard ship or in a submersible, the high cost of ship operations and equipment, and the long lead time of grant and project funding, pressure testing makes sense to validate system integrity before deployment. Simply put, equipment should not see pressure for the first time on its first operational deployment. Pressure testing is a vital environmental check of mechanical integrity, analogous to electronics and software burn-in. Ideally, pressure testing will simulate the actual conditions of deployment and operation. A solid test provides the operator and deck crew confidence in the system being deployed.While pressure testing will appear to add time and cost, in practice it saves both by eliminating failure modes, some potentially catastrophic, while offshore.This technical note is intended to summarize current best practices in pressure testing for engineers and programs managers new to the field, including tips for coordinating work with pressure test facilities. The lessons are based on the authors’ combined experience as users and operators of pressure test facilities.

Ceramic Spheres—A Novel Solution to Deep Sea Buoyancy Modules

“…Both are industrial standard test methods and are generally considered to be the most efficient methods for validating the design of prototypes. Although some other non-destructive proof tests are used in industry for qualifying buoyancy modules at a given pressure rating [ 12 ], we mainly used the ceramic sphere CS T10 samples for the pressure proof test. As previously mentioned, the applied isostatic pressure (83 MPa) corresponds to a depth rating of 3660 m below sea level with a safety factor of 3.…”

“…Various characterizations were carried out to investigate such ceramic spheres in terms of structure, sphericity, buoyancy and mechanical properties. The isostatic compressive strength of the ceramic hollow spheres has been considered the most critical product criterion, as they could burst due to over pressure and result in implosions during service [ 6 , 12 ]. Hence, a proof pressure test has been deployed in this study and has demonstrated that the ceramic spheres successfully withstand a short-term pressurization without any failure or implosion.…”

A preliminary design of a movable laboratory for hadal trenches

“…Pressure testing remains one of the most useful tools designers have available to assure their systems function as intended (Hardy and James, 2009). In the development of the JIAOLONG deep manned submersible, the safety of the manned cabin was tested at 1.1 times of the maximum operating pressure, that is, at 78 MPa in the pressure chamber.…”

Design of a Practical Metal-Made Cold Isostatic Pressing (CIP) Chamber Using Finite Element Analysis

“…Pressure testing with a deep-ocean pressure chamber (DOPC) is a fast and effective method to validate the safety of deep-ocean engineering equipment [ 1 ]. To develop full-ocean-depth (FOD) submersibles, large biomimetic robotic fish, new buoyancy materials, and so forth require a DOPC with a large inner diameter and ultra-high-pressure (UHP) [ 2 ].…”