HDS Safety Anchor

What a heavy duty safety anchor is

The HDS is a torque-controlled expansion anchor for concrete. It is driven through the fixture into a drilled hole, and tightening the nut or bolt to the installation torque pulls the threaded cone into the expansion sleeve, which presses out against the hole. A distance sleeve runs from the expansion sleeve up through the fixture hole. Hobson's HDS anchors are declared under ETA-02/0030 (Highload Anchor SZ, issued by the Deutsches Institut fur Bautechnik), and the ETA's assessment assumes a working life of at least 50 years.

Hobson lists the HDS for high-risk and safety-critical applications, structural applications, major infrastructure, and bridges and tunnels. Bolting steel base plates, columns, barriers and plant to slabs is a common use. These are engineered fixings: the ETA says anchorages are designed under the responsibility of an engineer experienced in anchorages and concrete, so the anchor, size, embedment, spacing and edge distance come from that design.

• •HDS-N (stud and nut, the ETA's SZ-B): a threaded stud with a nut and washer. Zinc plated M8 to M20, and 316 stainless M10 to M16.
• •HDS-B (hex head bolt, the ETA's SZ-S): a hex head bolt instead of the stud and nut. Zinc plated M6 to M20.
• •HDS-K (countersunk, the ETA's SZ-SK): a countersunk screw and countersunk washer with a T50 drive, for a flush finish in a countersunk fixture. Zinc plated M12 x 115.

Option 1, seismic C1 and C2 and fire: what they mean

• •ETA Option 1: Hobson's article on ETAG options explains that Option 1 in ETAG 001 is the test regime for safety critical anchors to be used in ceilings, under cracked or non-cracked conditions. Every HDS we carry is Option 1, for cracked and non-cracked normal weight concrete C20/25 to C50/60.
• •AS 5216: Hobson's AS 5216 compliance note says anchors must be assessed to their European Assessment Document, with the values summarised in an ETA and used as the standard provides; for post-installed mechanical anchors that is EAD 330232. ETA-02/0030 is issued on EAD 330232-00-0601, and Hobson labels the HDS AS 5216.
• •Seismic C1 and C2: the ETA gives seismic performance categories C1 and C2 for the zinc plated SZ-B and SZ-S from M8 up and for the 316 sizes, and C1 and C2 for the countersunk M8 to M12. The M6 (HDS-B M6 x 115) has no seismic category: Hobson labels it Option 1 and fire only.
• •Fire: the ETA gives fire resistance values from R30 to R120 and a reaction to fire class of A1, for every size we carry.

HDS safety anchor sizes

Size is thread x anchor length in mm. The drill is much bigger than the thread, because the hole takes the sleeve: an M12 HDS needs an 18mm hole. Max. fixture is the thickest part the anchor fixes through at its standard setting depth: it is the number after the slash in Hobson's description, which Hobson's HDS-B Did You Know sheet confirms as the maximum fixture thickness. Select a row to open that code in the selector.

Installation values, zinc plated HDS (ETA-02/0030 Table B1)

The ETA sets the hole, embedment, torque and member thickness for each size. The effective anchorage depth (hef) can be anywhere from the minimum to the maximum shown; a deeper setting takes the same anchor further into the slab, and the ETA reduces the usable fixture thickness by the extra depth. Use a calibrated torque wrench for the installation torque.

Conditions behind every value: hammer drilling only (vacuum drill bits are allowed); normal weight concrete C20/25 to C50/60, cracked or uncracked; the zinc plated anchors in structures subject to dry internal conditions only; used as supplied without replacing parts; installed by qualified personnel under the supervision of the person responsible for technical matters on site.

Installation values, 316 stainless HDS-N (ETA-02/0030 Table B2)

The 316 (A4) anchors have their own table in the ETA, with higher torques for the stud and nut version. Do not use the zinc plated torques on a 316 anchor.

Edge distance and spacing

The ETA gives each minimum spacing only with at least a set edge distance, and each minimum edge distance only with at least a set spacing, separately for cracked and uncracked concrete. Intermediate values are found by linear interpolation. Where fire can attack from more than one side, the edge distance must be at least 300mm. These are the closest the ETA allows, not distances at which the anchor carries its full load: near these minimums the design resistance drops, and the engineer works out what each anchor can carry using the ETA's characteristic values and EN 1992-4. That is why we do not print load figures here.

How to install an HDS safety anchor

1. Check the design: anchor style, size, embedment, positions, edge distances, spacing and slab thickness come from the engineer's design, within the minimums above.
2. Drill the hole at right angles to the concrete surface, by hammer drilling, at the drill size for the anchor (for example 18mm for M12) and at least the hole depth in the table.
3. Blow the dust out, or vacuum to the bottom of the hole. With a vacuum drill bit you can go straight to the next step.
4. Drive the anchor in through the fixture with a hammer.
5. Check the setting depth: the ETA shows a mark on the anchor for the minimum effective embedment (hef,min). Make sure the anchor is driven in to at least that mark. If it is set deeper, the ETA reduces the usable fixture thickness by the extra depth (hef minus hef,min).
6. Tighten to the installation torque for that size and version with a calibrated torque wrench.

Zinc plated or 316 stainless?

The ETA decides this. Zinc plated HDS anchors are for structures subject to dry internal conditions only. The 316 (A4) HDS-N is also for external atmospheric exposure, including industrial and marine environments, and permanently damp internal conditions, provided there are no particularly aggressive conditions: the ETA names permanent or alternating immersion in seawater, the seawater splash zone, the chloride atmosphere of indoor pools and atmospheres with extreme chemical pollution. So in the open, by the coast or in damp plant rooms, use the 316 HDS-N; near a pool or in the sea, ask the designer for an anchor assessed for those conditions.

Hobson's coatings chart rates zinc plating (5 micron) as low corrosion resistance, for indoor and non-corrosive environments, which matches the ETA. Hobson's stainless article adds that 316 is not made to sit in seawater: seawater carries about 20 times the chloride 316 can withstand.

Safety anchor, wedge anchor or chemical anchor?

• •HDS safety anchor: a torque-controlled sleeve-type anchor with a distance sleeve, ETA Option 1, seismic C1 and C2 from M8 and fire values, in stud and nut, hex bolt and countersunk versions.
• •Clawbolt PRO wedge anchor: a stud anchor with an ETA, drilled at the thread size; seismic and fire approvals vary by code, see the wedge anchor page.
• •Mungo HL heavy duty shield anchor: a similar three-head range; Hobson's documents for that page show no ETA, seismic or fire approval.
• •Chemical anchor: a resin-bonded anchor with no expansion forces in the concrete; approvals and base materials are on the chemical anchor page.

Safety anchors in Adelaide

Allmat supplies HDS safety anchors, Clawbolt PRO wedge anchors, chemical anchors and SDS drill bits to builders, steel fabricators, structural and services installers across Adelaide and South Australia. Send us the anchor schedule from your engineer's design and we will price the lot.

Questions