AUMA GS 250.3 Part-Turn Worm Gearbox (56,000 Nm)

Overview

AUMA GS 250.3 is the largest gearbox in the GS 50.3 to GS 250.3 series, rated for 56,000 Nm of valve torque in standard open-close duty and 70,000 Nm for valves that are rarely cycled. It is the gearbox behind the very large butterfly valves, ball valves and plug valves found in hydroelectric penstocks, cooling-water culverts and pipeline terminals, where valve diameters are measured in metres and a single closing stroke moves a considerable mass of water or gas. At 273 to 308 kg it is a lifting job in its own right, so sizing and ordering it correctly the first time matters more than for any smaller frame.

In Oman and the GCC, Seven Star LLC supplies the AUMA GS 250.3 to major infrastructure and energy projects in the Sultanate of Oman and the GCC.

Gear Train and Duty of the AUMA GS 250.3

The AUMA GS 250.3 turns the quarter-turn valve through a worm and worm wheel set housed in cast iron, with an integral spigot and a splined coupling that is delivered without bore or with a pilot bore. As with the other GS sizes the gearbox is self-locking at standstill under normal service conditions, positive end stops are formed by a travelling nut, and the swing angle is adjustable between 80 and 100 degrees as standard with optional ranges up to 190 degrees. The mean output torque for ATEX duty is 32,000 Nm over three OPEN-CLOSE-OPEN cycles.

Five ratios define the operating envelope: 52:1 (factor 20.3, 13 turns), 210:1 (74.0, 52.5 turns), 411:1 (144, 103 turns), 848:1 (263, 212 turns) and 1,718:1 (533, 430 turns). A valve that demands the full 56,000 Nm needs 2,759 Nm at the input on the 52:1 ratio, 757 Nm at 210:1, 389 Nm at 411:1, 213 Nm at 848:1 and 105 Nm at 1,718:1. The guaranteed end stop strength is 8,000, 2,000, 1,000, 500 and 250 Nm in the same order, and the fastest 90-degree times are 7, 15, 29, 59 and 119 seconds. Lifetime at maximum torque is 1,200 cycles in duty class 1 and 1,000 cycles in duty class 2.

Engineering Design of the AUMA GS 250.3

Valve attachment follows EN ISO 5211 with flanges F35, F40 and F48 and a maximum shaft diameter of 160 mm, where the F48 flange is carried by an extension flange that is screwed and doweled to the housing and adds 75 kg. The input shaft ranges from 50 mm on the 52:1 ratio down to 20 mm on the highest ratio, and the input mounting flange falls from F30 (F25) through F16 (F14) and F14 to F10, so the same housing accepts everything from an SA 30.1 class actuator down to an SA 10.2.

Weight is 273 kg for the 52:1 ratio, 296 kg for the 210:1 and 411:1 ratios and 308 kg for the two highest ratios, including the unfinished coupling and grease filling. Enclosure protection is IP68, corrosion protection is KS, and the standard temperature range is -40 to +80 degrees Celsius. The housing is cast iron, with a spheroidal cast iron housing available as an option, and handwheel operation under duty class 3 is rated to the same 70,000 Nm figure as duty class 2.

Ratio Table for the AUMA GS 250.3

The five ratios of the AUMA GS 250.3 give a wide choice of actuator size and closing time, as the AUMA data sheet figures below show.

All ratios except 52:1 are equipped with primary reduction gearing or planetary gearing to reduce input torque, and the 52:1 ratio is the only one that needs more than 800 Nm at the input shaft.

Key Features

The AUMA GS 250.3 is the answer when the valve, not the actuator, sets the torque requirement:

• Maximum valve torque of 56,000 Nm in duty class 1 and 70,000 Nm in duty classes 2 and 3.
• Five ratios from 52:1 to 1,718:1 so that input torque can be reduced from 2,759 Nm to 105 Nm.
• Valve flanges F35, F40 and F48 to EN ISO 5211 with a shaft capacity of 160 mm.
• Fastest 90-degree operating times of 7 to 119 seconds depending on the ratio.
• Guaranteed end stop strength up to 8,000 Nm for input side operation.
• F48 attachment through a 75 kg extension flange screwed and doweled to the housing.
• Weight of 273 to 308 kg depending on ratio, which calls for crane-assisted handling.
• Lifetime of 1,200 cycles at maximum torque in duty class 1, IP68 enclosure and KS corrosion protection.

Industrial Applications

Hydroelectric turbine inlet valves, seawater cooling culverts at coastal power and desalination plants, and LNG or crude pipeline isolation valves are typical homes for the AUMA GS 250.3. The very high torque comes from the sheer diameter of the valve disc rather than the pressure alone, and a closing stroke has to be slow enough to avoid surge, which is exactly what the 411:1 to 1,718:1 ratios provide with closing times from 29 to 119 seconds. Oman’s large coastal utilities and export terminals are therefore natural customers for this gearbox size.

In Oman and the GCC, Seven Star LLC supplies the AUMA GS 250.3 with matching SA actuators to EPC contractors and plant operators across Oman and the GCC, with project coordination for Sohar, Duqm and Salalah. See also the AUMA GS part-turn gearbox range, the AUMA SA 10.2 multi-turn actuator for light-duty cases and the AUMA LE linear thrust unit for rising-stem valves.

Related pages on our site: AUMA GS 160.3, AUMA GS 400 and AUMA GHT heavy-duty worm gearbox.

Technical Specifications

For the AUMA GS 250.3 the same combined sheet lists five ratios, and the principal values are repeated here.

On the AUMA GS 250.3, a ratio of 210:1 brings the input requirement down to 757 Nm and 848:1 to 213 Nm, at 15 s and 59 s respectively, so the closing time allowed by the process often decides between them.

Request a Quote for AUMA GS 250.3

Submit your RFQ for the AUMA GS 250.3 with the valve torque, the closing time, the EN ISO 5211 flange and the intended multi-turn actuator, and Seven Star LLC will return a ratio recommendation and a delivery plan. The AUMA technical data sheet for this gearbox size can be downloaded from this page, and our team in Muscat advises on heavy lifting, extension flange fitting and commissioning. We supply AUMA products in Oman and the GCC and quote every unit on request.