Enerpac HMT3500 Modular Hydraulic Torque Wrench Drive Unit

HMT3500 is the 3750 ft.lbs (5084 Nm) drive unit of the Enerpac HMT modular hydraulic torque wrench series. The tool is a lightweight 1.8 kg (3.97 lb) drive that takes one attachment at a time: an HLP low profile hexagon cassette covering 35 to 80 mm (1 3/8 to 3 1/8 in) across flats, or an HSQ3500 square drive cassette. Both Enerpac and the instruction sheet describe it as a system that can also mate with cassettes from other well-known brands.

Modular design for mixed bolting jobs

A bolting crew rarely meets one fastener type. With the HMT3500 the drive unit stays the same while the cassette changes: the HLP hexagon cassette hooks around the top retaining pin of the drive and is secured by a bottom retaining pin, and the HSQ cassette fits the same way. Enerpac says the drive unit uses superior alloys and surface treatments to be lightweight, up to 25% faster and twice as durable as other tools in its class, which are the manufacturer’s own comparative claims.

The tool is supplied with an ergonomic safety handle and a link pin retainer as standard, and Enerpac states that it ships with a calibration certificate. Output torque is constant, with accuracy of +/-3% across the full stroke.

Key features as printed in the datasheet

• Maximum torque 5084 Nm (3750 ft.lbs); minimum torque 508 Nm (375 ft.lbs).
• Weight 1.8 kg for the drive unit; cassettes add 4.0 to 5.0 kg (HLP) or 4.1 kg (HSQ3500).
• Interchangeable with cassettes of other manufacturers, as stated on the Enerpac page.
• Standard ergonomic safety handle and link pin retainer.
• ATEX: the product page says all HMT tools are CE – ATEX certified; the instruction sheet prints the mark Ex II 2 G c T6.

Technical specification

Drive unit data (Enerpac product page and instruction sheet L4478)

Cassette data for HMT3500 (manual tables 4.2 and 4.4)

Pressure to torque, selected points (manual table 4.5.2)

Selection and ordering guide

Order codes named by Enerpac for this drive unit are the HLP hexagon cassettes HLP3106 to HLP3115, HLP3200 to HLP3215 and HLP3300 to HLP3302, and the HSQ3500 square drive cassette. Pump pressure sets the torque by the instruction sheet formula: pump pressure (psi) equals torque (ft.lbs) divided by the torque factor 0.3750. For a 2250 ft.lbs target the result is 6000 psi, a derived value you should confirm against the manual’s table.

The HMT series has four sizes (HMT1500, HMT3500, HMT7500 and HMT13000 at 1541, 3750, 7562 and 13,489 ft.lbs). The loosening rule on the Enerpac page applies: loosening torque is about 250% of tightening torque, so size the tool for the breakout case.

Installation and operation notes

Hoses are a twin-line 10,000 psi (690 bar) assembly. One line of each twin hose must be male-male and the other female-female, and an even number of twin hoses between pump and wrench must never be used, because high pressure would then sit on the retract side. Connect the female coupling to the wrench advance port and the male coupling to the retract port.

Before use, engage the rod end with the drive pin in the cassette by turning the ratchet or square drive back and forth a quarter turn; Enerpac warns that damage from skipping this is not covered under warranty. Take reaction on a firm surface such as an adjacent nut, or fit the extended reaction arm or reaction paddle. The manual sets service intervals of 3, 6 or 12 months for heavy, normal and infrequent use.

Applications in Oman and the GCC

The ATEX marking makes this wrench relevant to hazardous-area bolting, but the sheet is strict about conditions: do not use it above 40 C (104 F) ambient, avoid dropping it or impacts with corroded steel, and use only in the atmospheres it was tested for. In hot Gulf summers that ambient limit is worth checking at the work location. General use is flange and bolted-joint work in refineries, petrochemical plants and power stations.

Compatible accessories and related items

Named in the sources: HLP and HSQ cassettes, extended reaction arm and reaction paddle, THQ700 series hoses, and the service kits HMT3500SK (seals), HMT3500BCK (back cap), HMT3500TRK and HMT3500BRK (retaining pins) and HMT3500GSK (grub screw).

Frequently asked questions

What is the maximum torque of the Enerpac HMT3500?

5084 Nm (3750 ft.lbs) at 10,000 psi / 690 bar, with a minimum of 508 Nm (375 ft.lbs).

Which cassettes does the HMT3500 take?

HLP hexagon low profile cassettes (HLP3106 to HLP3302 as listed) and the HSQ3500 square drive cassette; one attachment is used at a time.

Is the HMT3500 rated for explosive atmospheres?

The page states CE – ATEX certification and the manual prints Ex II 2 G c T6. The manual limits use to 40 C ambient and warns against impacts with corroded steel.

How is torque set on the HMT3500?

By pump pressure: pressure in psi equals the required ft.lbs divided by 0.3750, or read the printed pressure-to-torque table in the instruction sheet.

Can Seven Star LLC quote the HMT3500?

Seven Star LLC is an independent supplier in Muscat and quotes this item on request; send quantity and site details through the enquiry form.

Documents and quotation

Instruction sheet L4478 Rev. G for the HMT series (English, 48 pages) is hosted here for download and covers HMT1500 to HMT13000, so read the HMT3500 columns. Seven Star LLC is an independent Muscat supplier and quotes on request. Confirm cassette, hose and pump choices in the sheet before ordering. Related tools: category.