ASME B16.48 covers line blanks: spectacle blinds (figure-8 blanks), paddle blanks and paddle spacers that are installed between pipe flanges to positively isolate a line, or to keep it open with a spacer of the same thickness. The standard sets their thickness, outside dimensions, handle, marking and pressure–temperature ratings so that a blank of a given class and size fits between standard flanges and holds the full line pressure.
Raaj Fittings manufactures spectacle blinds, paddle blanks and ring spacers to ASME B16.48 at our two plants in India, in carbon, low-temperature, alloy and stainless steel, duplex and nickel alloys.
Order the blank to the same class, facing and material as the flanges it sits between. Large and high-class spectacle blinds are heavy, so paddle blanks and spacers are often used above about 12" and in Class 600 and higher, together with lifting arrangements.
Every line blank is made from PMI-verified material, dimensionally inspected against the ordered standard and marked with material, size, rating and heat number. Orders are supplied with EN 10204 3.1 certificates; EN 10204 3.2 certification and inspection by the buyer's nominated third-party agency are available on request.
A spectacle blind combines a blank and a spacer in one figure-8 piece that is rotated between flanges. A paddle blank and paddle spacer are separate pieces that are swapped, which suits large or heavy sizes.
The blank must act as a flat plate holding full line pressure, so its thickness is set by size, pressure class and material in the standard.
Yes, line blanks are made with facings to suit ring type joint flanges as well as raised-face flanges.
The same or an equivalent material to the flanges it sits between, so that corrosion resistance and pressure rating match the line.