Access to an underground gas pressure regulating station in Frankfurt/Main

Awarded with the “M&T Metallbaupreis 2014” Category „doors, gates, fire protection“

Requirements of the customer

We won the contract for the design and planning of an access to an underground gas pressure regulating station. An above ground existing gas pressure regulating station had to be relocated underground, because the location was later to be used as public space.

The following requirements of the client had to be fulfilled for the materials supplying unit to the underground substation:

The flap cover must be passable for SLW30 (heavy trucks) with a wheel load of 50 kN.
The flap must be air-permeable.
For architectural reasons only the supporting bars of the flap grid should be visible.
The material of the flap has to be corrosion-resistant to road salt.
Emergency exit from and accessibility to the gas pressure regulating station in case of power failure.
Accessibility to the gas pressure regulating station after an explosion or the like.
Optimized design of the driving technology according to guide line 2006/42/EG.
The leveling of the access flaps must match with the inclination of the ambient floor and must have an anti-skid surface.
The power-operated flap must be approved by the safety authorities.

Planning phase

The planning phase included the following tasks:

Selection of stainless steel 1.4571, with a strength class S355 (XCrNiMoTi 17-12-2 (1.4571)) as material of choice.
Static layout of the steel grids and the anchoring in the reinforced concrete according to EN 1993 and AbZ Z-30.3-6, selection of strength class S355.
Anti-skid design of the flap grid surface.
Risk evaluation according to DIN EN ISO 14121-1 for the access- and flight-paths.
Selection and design of the hydraulic driving unit for the flap under consideration of guide line 2006/42/EG and EN 13241.
Creation of circuit diagrams and construction of the control cabinet.
Mechanical design of a manually operated emergency exit with redundancy in case of fire.
Establish the documents like operating manual according to EN 12635 and EN 62079 as well as an inspection log book.
Sketch-, design- and construction plans for the accesses of the gas pressure regulating station as CAD files.

Properties of the secure entrance

Hydraulic folding grate with special features

Features of the gate

Dimensions LXW:	4150 x 1450 mm
Weight:	2500 kg
Material:	Stainless steel (1.4571), strength S355
Support bar:	110 x 15 mm
Tolerance of the steel structure:	+/- 2 mm
Ribbons:	Turned and milled from 1.4571, bronze bushes to avoid contact corrosion with stainless steel.
Freeze protection:	Angle support is heated against freezing in winter
Shape of the bearing bars:	Ensuring targeted load application through the blank contour
Profiling:	Special cutting with subsequent glass bead blasting to achieve a suitable anti-slip class
Installation position:	Inclination 1.6° around one axis
Hydraulic power unit	Power 2.2 kW, operating pressure: 100 bar, with gear pump, with check and brake lowering valve, opening in case of power failure possible via hand pump

Mechanical folding grate as 2nd escape route with special features

Features of the gate

Dimensions LXW:	1100 x 1150 mm
Weight:	500 kg
Material:	Stainless steel (1.4571), strength S355
Support bar:	110 x 10 mm
Tolerance of the steel structure:	+/- 2 mm
Ribbons:	Turned and milled from 1.4571, bronze bushes to avoid contact corrosion with stainless steel.
Freeze protection:	Angle support is heated against freezing in winter
Shape of the bearing bars:	Ensuring targeted load application through the blank contour
Profiling:	Special cutting with subsequent glass bead blasting to achieve a suitable anti-slip class
Installation position:	Inclination 1.6° around one axis
Redundant winch mechanism	To be opened from the outside, by turning a shaft which is directly connected to the drive gear. Opening inside through a handwheel, which is connected to the drive gear. Pre-set gear, for a manual force of <5 N. 2 pcs. Winches (to provide redundancy), each of which is capable of carrying the grate load alone. The calculations for the dimensioning were made by us