OsecoElfab’s POSIPRO Rupture Disc

OsecoElfab’s bi-directional POSIPRO discs are excellent for applications requiring both positive and vacuum pressure protection. The POSIPRO is used in applications requiring extremely low positive pressure relief. It can activate as low as 6″ Water Column (W.C.). As pressure within a vessel approaches the disc set pressure, a girdle is loaded until it collapses back past a knife blade assembly, opening the seal. Under vacuum conditions, a perforated metal top section activates at a predetermined set point, just like a model CO rupture disk.  The positive burst pressure range encompasses 6″ – 30″ (W.C.), with a vacuum burst pressure range of 4 psig to 14.7 psig.  With sizes ranging from 3” to 10”, the POSIPRO is ideal for applications that need an inexpensive, dual-setpoint pressure safety device. The POSIPRO is considered a “composite” rupture disk because it always incorporates at least three distinct layers: a metal slotted top section (which controls the vacuum burst pressure), then a slit-slot Teflon cover layer (which separates the metal above from the seal below), then a solid fluoropolymer seal (a solid sheet which holds back the process fluid and prevents leakage). Finally, a flexible, stainless-steel girdle, which controls the positive set pressure is added to the bottom of the disk assembly.  The POSIPRO is designed for operation in applications where normal system pressures do not exceed 80% of the stamped burst pressure.

  • The POSIPRO is available in line sizes ranging from 3 inch diameter all the way up to 10 inches diameter.
  • The POSIPRO is available in positive burst pressures ranging from 6 inches water column all the way up to 30+ inches water column.
  • The POSIPRO is available in vacuum burst pressures ranging from 4 psig all the way up to 150 psig.
  • The POSIPRO is available in burst temperatures ranging from cryogenic temperatures all the way up to 400 degrees F.
  • The POSIPRO is available in all OE standard materials (316 Stainless Steel, Nickel 200, Inconel 600, Monel 400, and Hastelloy C 276).  Other materials may be available or offered on request.
  • The POSIPRO works well in gas or vapor services, as well as liquid or two-phase services.
  • The POSIPRO is not ASME UD stamped. A default Kr value of 2.4 must be used when performing sizing calculations with this rupture disk.
  • The POSIPRO has an 80% operating ratio, meaning the POSIPRO operates reliably and with a long service life at pressures up to 80% of the marked burst pressure.  Pressure excursions above this 80% operating ratio will shorten the lifespan of the POSIPRO.
  • The POSIPRO is offered with a standard 0% Manufacturing Design Range (MDR), meaning there will never be any variation between what burst pressure you order, and what burst pressure is marked on the tag of the rupture disk.
  • The POSIPRO uses a custom burst tolerance for the positive set pressure of + 6 inches water column of marked burst pressure. The POSIPRO uses an ASME standard tolerance for vacuum set pressures of +/- 2 psig of marked burst pressure.
  • The POSIPRO is a non-scored metal rupture disk, with potential for fragmentation. This means the POSIPRO, and composite rupture disks in general, cannot and should not be installed upstream from a pressure relief valve.
  • The POSIPRO is not offered with a vacuum support, as it is designed to burst at a specific vacuum rating.
  • The POSIPRO is designed to be installed into the POSI rupture disk holder.
  • The POSIPRO is both a forward acting metal rupture disk, and a Teflon reverse acting rupture disk.  Vacuum is applied to the convex side of the rupture disk.  Increasing vacuum stretches the metal center section of the rupture disk until the metal yields and tears open between the holes drilled into the disk. Positive process pressure pushes the Teflon seal up into knife blades, welded into the VRDI holder, causing the Teflon seal to puncture and cut open along the knives.
  • The POSIPRO, like all forward acting, metal rupture disks, does best in static pressure applications.  The POSIPRO handles pressure cyclic services fairly well, but reverse acting metal rupture disks are typically recommended, to ensure the tag stays attached to the disk for services with oscillating pressures.
  • The POSIPRO is not designed, manufactured, nor certified to ASME BPVC Section XIII requirements.
  • The factory must be consulted for MNFA values for the POSIPRO rupture disk.
  • For a 3” POSIPRO, the positive burst pressure range for all the standard OE materials (316 Stainless Steel, Nickel 200, Inconel 600, Monel 400, and Hastelloy C 276) runs from a minimum of 6 inches water column up to a maximum of 30 inches water column. The vacuum burst pressure ranges from a minimum of 11 psig down to a maximum burst pressure of 14.7 psig.
  • For a 4” POSIPRO, the positive burst pressure range for all the standard OE materials (316 Stainless Steel, Nickel 200, Inconel 600, Monel 400, and Hastelloy C 276) runs from a minimum of 6 inches water column up to a maximum of 30 inches water column. The vacuum burst pressure ranges from a minimum of 8 psig down to a maximum burst pressure of 14.7 psig.
  • For a 6” POSIPRO, the positive burst pressure range for all the standard OE materials (316 Stainless Steel, Nickel 200, Inconel 600, Monel 400, and Hastelloy C 276) runs from a minimum of 6 inches water column up to a maximum of 30 inches water column. The vacuum burst pressure ranges from a minimum of 6 psig down to a maximum burst pressure of 14.7 psig.
  • For a 8” POSIPRO, the positive burst pressure range for all the standard OE materials (316 Stainless Steel, Nickel 200, Inconel 600, Monel 400, and Hastelloy C 276) runs from a minimum of 6 inches water column up to a maximum of 30 inches water column. The vacuum burst pressure ranges from a minimum of 5 psig down to a maximum burst pressure of 14.7 psig.
  • For a 10” POSIPRO, the positive burst pressure range for all the standard OE materials (316 Stainless Steel, Nickel 200, Inconel 600, Monel 400, and Hastelloy C 276) runs from a minimum of 6 inches water column up to a maximum of 30 inches water column. The vacuum burst pressure ranges from a minimum of 4 psig down to a maximum burst pressure of 14.7 psig.