ASME PVHO-2-2012 pdf download

ASME PVHO-2-2012 pdf download.Safety Standard for Pressure Vessels for Human Occupancy:ln-Service Guidelines.
2-3.1 Cleaning and Polishing
2-3.1.1 Correct Methods. Windows may be cleaned to restore optical quality or clarity as the need arises. The window should only be wiped with a soft rag or cloth (or a very soft type of paper towel) wetted with warm water and an acceptable cleaning agent. As any use of power tools requires annealing, cleaning and! or polishing by hand is the only acceptable in-service method.
The recommended agent to clean windows is a detergent in solution in warm water not exceeding 120°F (49°C). Aliphatic naphtha or hexane are also acceptable, but only if the temperature of the window surface does not exceed 100°F (38°C).
After cleaning, window surfaces may be polished with compounds specifically endorsed by the manufacturer for polishing of acrylic. These compounds are also used for removing small scratches from the surface. See Mandatory Appendix V for a partial listing of acceptable cleaning products and polishing compounds.
2-3.1.2 Incorrect Methods. Solvents shall not be used for cleaning windows. If solvents are used on the seats, extreme care shall be taken to ensure that drying! evaporation of the solvent is complete prior to window installation. Mandatory Appendix V provides a list of harmful substances.
Power polishing shall not be performed unless the window is subsequently annealed and pressure tested, per the requirements set forth in Mandatory Appendix IV.
2-3.2 Window Storage
An unused acrylic window may be stored for up to 10 yr from the date of fabrication without the storage time counting toward the service life, provided the storage conditions meet the following requirements:
(a) The window is stored at a temperature not exceeding 125°F (52°C).
(b) The window is protected from exposure to direct or indirect sunlight.
(c) The window is protected from wetting and drying.
(d) The window is protected from exposure to harmful chemicals (both liquid or gaseous).
(e) Windows shall be stored flat and shall not be stacked; that is, they shall not be stored resting on their edges, or with any weight bearing on them.
‘f) The date storage begins is the date of manufacture; thus, the date of installation shall be recorded and retained as a permanent record.
(g) Any storage time in excess of 10 yr shall be included, day for day, in the service life of the window.
In addition to inspecting the other viewport components, all window surfaces (and edges) described in Table 2-4.1-1 shall be inspected to the criteria set forth in Tables 2-4.1-2 through 2-4.1-4. Special optical devices, such as prisms, optical measuring devices, and coherent fiber bundles, are often useful for these inspections.
At the discretion of the inspector, components of a viewport may need to be removed for a more detailed inspection.
When refurbishing viewports (see Table 2-4.3-2), complete removal of the window is required.
PVHO-2 Form VP-i, Viewport Inspection, shall be completed and signed by the inspector. Additional information may include photographs and schematics, and should be retained with the Viewport Inspection form.
Records of the MV1 shall be retained throughout the service life of each window, plus 5 yr.
2-4.3.1 Maintenance Viewport Inspection Schedule.
The user is responsible for establishing a procedure and schedule for the maintenance viewport inspection. Scheduling shall take into account the service environment and whether or not the service life of the window is less than or greater than its design life.
Maintenance viewport inspections shall be performed
(a) as a minimum, at intervals shown in Table 2-4.3-1
(b) at refurbishment intervals shown in Table 2-4.3-2
(c) when a window is removed and reinstalled
(d) when a new window is installed
(e) for windows that have been out of service for 18 months or longer
2-4.4 Limitations on Service Life
The service life of windows in a PVHO operated in a protected service environment may be extended beyond the design life on the basis of visual inspections alone. However, no window may remain in service for more than 10 yr or 5,000 cycles beyond its design life, unless one or more windows from that PVHO are tested in accordance with subsection 2-7. (The exception is cylindrical window chambers, which may be operated for up to an additional 10,000 cycles max., prior to replacement.)
The service life of windows in a PVHO operated in a severe service environment may not be extended beyond the design life on the basis of visual inspections alone. Any service life duration extension beyond the design life shall be justified by the test procedures of subsection 2-7.