Double-block-and-bleed manifold

Citation

(2003), "Double-block-and-bleed manifold", Anti-Corrosion Methods and Materials, Vol. 50 No. 1. https://doi.org/10.1108/acmm.2003.12850aad.009

Double-block-and-bleed manifold

Double-block-and-bleed manifold

Keywords: Manifold, Instruments, Pipelines, Leaks

Parker Instrumentation has released a novel new style of double-block-and-bleed manifold, based on a one-piece construction that is said to eliminate numerous potential leak paths compared with traditional assemblies.

Providing very high integrity – and additionally reducing size and weight – the manifold is thought to be ideal for implementing instrument take-offs wherever reliability and/or compactness are important, and includes chemical/petrochemical plants.

Called Pro-Valve, the new manifold is fabricated from a one-piece valve body forged in the popular weldolet style, and requires just two joints: a welded joint at one end for connection to the process pipe, and a joint at the other end for connecting the instrument. The latter joint can be specified in the form of either standard thread, or an integrated compression tube fitting.

This arrangement greatly reduces the number of potential leak paths in instrument take-offs by eliminating the need for flanged connectors to the pipeline, and with it, the use of problem-prone taper thread interfaces (which rely on the use of additives to ensure a seal – opening avenues for system contamination or mis-assembly). If integral tube fittings are specified for the instrument connection side of the manifold, this eliminates taper threads from the entire system – further boosting integrity.

Pro-Valve is rated for pressures to ANSI class 4500, and may be ordered with weld profiles to suit pipes from 314 to 36 inches in diameter. In addition to a choice of instrument interface (male or female threads in NPT, BSPT, BSPP or gauge sizes, or A-LOK or CPI twin- or single-ferrule tube fittings) users can specify Pro-Valve with either needle or OS and Y (outside screw and yoke) styles of isolation and vent valves, and in a range of materials to combat corrosion including 316L, monel, duplex, super duplex, hastelloy, incoloy and 6Mo.

The use of a one-piece forging substantially reduces the size of instrument take-offs. After welding to the pipe, the typical height to the top of the manifold is just 150 mm (6 inches). This is probably 25 per cent of the height of an assembly using separate flanged connectors and manifold.

Weight is also greatly reduced, with Pro-Valve weighing around 3.5 kg in its smallest variant.

A free brochure is available by e-mailing <manifolds@parker.com>

Details available from: Parker Hannifin, Tel: +44 (0) 1271 313131; Fax: +44 (0) 1271 373636; E-mail: ipd@parker.com