One Way Webbing Sling

A one way webbing sling is a rated polyester sling bought for one journey: it is fitted to the load, travels with it and is written off against that job instead of being returned to a sling store. This page covers the closed gelung tidak berkesudahan form — the shape specified for pipe, tube and bundling work, because a loop wraps a cylinder instead of hooking it. Julat standard: 1 t kepada 12 t, lebar jalur 25 mm ke 300 mm, faktor keselamatan 5:1, 6:1 atau 7:1, panjang gelung 0.5 m ke 100 m, marked to BS EN 1492-1.

What “one way” decides, dan apa yang tidak

The phrase describes the commercial life of the article, not its quality. A one way sling is manufactured, bukti dimuatkan, colour coded and labelled to the same standard as a sling that will be inspected for years; the difference is that it leaves the store once and does not come back.

Three practical consequences follow. Ia adalah dikeluarkan dengan beban, so it becomes a line on the packing list rather than an item in a sling register. Ia adalah inspected once, pada titik isu, while a fault can still be replaced from the same consignment. And its print is its whole record: had beban kerja, panjang, factor and batch are the only traceability the band will ever carry, so the marking has to survive a lorry, a container and a loading bay — not just the production line.

What it does not change is the engineering. A narrow band or a lower factor chosen because “it is only going one way” is not a saving; ia adalah margin tidak dinilai yang diambil daripada lif. The figure that applies is the figure printed on the band, for the arrangement actually used. Buyers who need the returnable version of the same loop should read the anduh rata tak berkesudahan lapis tunggal page instead.

Why a closed loop is the right form for pipe, tube and bundles

An endless webbing sling is a band joined to itself. There is no eye to line up against a machined pipe end, no stitching stack at the bearing point and no shackle, hook or thimble anywhere on the article. On round loads that single property does most of the work.

• It cannot mark a coating. Galvanising, fusion bonded epoxy, three layer PE and paint are all damaged by the same things: a steel edge, a sliding hook and point pressure. A woven polyester face addresses all three. Nothing metallic contacts the pipe, and the load never slides against a fitting.
• The choke holds itself. Passed round the pipe and back through the loop, the band tightens as the load rises. On a cylinder the contact line is a full wrap rather than two point contacts, which is why a loop resists slipping along the axis and does not walk towards the pipe end during a pick.
• The load stays centred. Because the band wraps symmetrically, the pick point sits over the centre of gravity of a joint or bundle rather than off one side — the usual cause of a tilted, eccentric lift and of one sling taking more than its share.
• Pressure is spread by width. Thin wall PVC, PE and stainless tube dent under a narrow band. A 100–200 mm face turns a point load into a low pressure band, which is the single most effective protection on a soft or thin walled pipe.
• Nothing to lose and nothing to thread. A band with end fittings can arrive with the fittings gone. A loop is one piece of webbing: it is either there or it is not, and the person re-slinging at the far end needs no rigging plan to use it.

Where a one way webbing sling is used

The loop is chosen where the load is wrapped rather than hooked, and where the surface matters as much as the tonnage. On a joint lifted on its own, one loop goes round the pipe near each end and the two legs meet at the hook; on a bundle, one loop per pick position is choked round the pack. The applications below are the ones this range is most often bought for, and each one puts a different line on the enquiry.

Specifications of the one way webbing sling

The figures below describe the standard build. Lebar bukan pilihan bebas: it follows from the working load limit and from the safety factor, so the same tonnage appears at three widths. Panjang gelung, lapis, colour and print are made to the order.

Choosing the size: the figure from the pick, the width from the surface

Two decisions are made separately and in this order. The had beban kerja comes from what one pick has to carry, divided by the mode factor of the hitch — not from the mass of the load as weighed. The lebar then comes from the surface being wrapped: a coated pipe and a painted machine at the same tonnage do not want the same band.

Panjang: the two conventions, and why the mistake is expensive here

A loop has no ends to measure between, so the trade quotes the same article two ways. The two figures differ by about a factor of two, and on a one trip band the error surfaces at the far end — in front of a customer, with no second band to swap in.

What the same loop carries in each hitch

The figure on the label describes the vertical arrangement only. All three hitches are rigged without any change to the article, which is why the arrangement has to be stated before the width is fixed.

Tercekik ialah susunan gelung yang dibeli, dan ia juga yang kosnya 20 % of the printed figure. A 4.5 t paip bundle tercekik a 5 gelung t ialah beban yang berlebihan, not a margin — the answer is the next width up, not a longer band.

Coating and surface compatibility

Menanda, label and what it has to survive

On a single trip article the print is the record, so the marking is a specification line rather than a detail. Four things belong on the label: had beban kerja, the loop length with its convention, faktor keselamatan, and the reference the despatch actually uses — a batch, nombor pek, nombor pesanan atau nombor bahagian anda sendiri. That reference is what ties the band on a quay to the line on a packing list in an office.

• Boleh dibaca selepas perjalanan, bukan selepas pengeluaran. Small, low contrast print on a face that enters the choke will not be read at the far end.
• Warna sebagai saluran kedua. Satu warna setiap jenis pek, per customer or per tonnage lets a container of identical bands be sorted at a glance.
• Printed to your string. The label can carry your reference in the exact case and format you send, dan band boleh dibungkus di dalam peti, diikat pada pegun atau dilekatkan ke dalam satu berkas, dilabelkan setiap pek.

The single inspection, and what it looks at

A one trip band is checked once, menjadi isu, while a fault can still be replaced from the same consignment. Look at four things, dalam susunan ini: the weave where it meets the load (luka, melecet, a glazed or pinched face), the join where the loop closes, the label — an unreadable figure cannot be matched to the pack it was cut for — and what the band has been lying in. Pasir, sekawan, minyak dan air bertakung bergerak ke dalam sentuhan, and a clean band is the cheapest protection available.

Protect the band from sharp edges, hot surfaces and welding spatter with a sleeve or a padded protector. Di atas 100 °C, or where sparks are present, polyester is the wrong fibre and an anduh bulat tidak berkesudahan with a heat resistant cover is the article to discuss.

One way or returnable: the arithmetic

The commercial case is simple and it is arithmetic, not preference. A one way band costs less per unit than a returnable sling and carries no return freight, tiada daftar pemeriksaan, no repair and no loss write-off — but it has to be counted correctly, because nothing comes back to cover a shortfall. Kira dari pek, bukan dari tonase: dua pick setiap pek ialah dua band, a four point lift is four, ninety packs at two picks is 180 pancaragam. Add two to five per cent for the band cut while the pack is made up, jadi kekurangan menjadi garis pada pesanan dan bukannya kelewatan di dok.

Where the same slings are used week after week in one yard, a returnable article inspected between lifts is the cheaper order over a year. Where the sling leaves with the load — export packing, one off shipments, work that ends on a customer’s site, or a coated pipe consignment that is re-slung at the far end — the one way loop is the right purchase. Where the whole consignment travels as a netted unit instead of being slung joint by joint, a jaring pengangkat kargo is the article to price against it. The form with eyes at both ends, for loads that are hooked rather than wrapped, adalah pada anduh sehala pakai buang muka surat; the wider family is on the anduh sekali pakai dan single use lifting slings endless loop muka surat.

What to send with the enquiry

Six lines are enough to quote a made to order band, and they remove every ambiguity that shows up later at the load:

1. The load — pipe diameter and wall, bundle mass, or the finished item.
2. The pick positions — how many, and how far apart.
3. The arrangement — vertical, tercekik atau bakul, and the angle if basket.
4. The girth at each pick, or the loop length with its convention named.
5. The safety factor your market works to, and the standard to mark to.
6. The reference to print, and the quantity per pack.

Soalan lazim

What is a one way webbing sling?

A rated polyester webbing sling supplied for a single journey. Ia bergerak dengan beban, is inspected once at the point of issue and is not recovered or re-issued. The endless form is a closed loop of flat woven polyester with no eye and no metal fitting, which is why it is the form chosen for pipe, tube and bundles.

Is a one way sling weaker than a reusable one?

Tidak. serat, menganyam, lebar, faktor keselamatan, working load limit and marking are specified exactly as for a returnable sling. Perkataan itu menggambarkan perjalanan, not the grade, so a lower factor or a narrower band is not a saving on a single trip article.

Will a webbing sling scratch galvanised or anti-corrosion pipe?

The band is synthetic fibre and no shackle, hook or thimble touches the load when an endless loop is used, so there is nothing to cut or gouge a zinc, epoxy or polyethylene coating. Lebar adalah ukuran perlindungan: semakin luas jalurnya, the lower the pressure at the contact.

How is the length of an endless webbing sling measured?

Two conventions are used and they differ by about a factor of two: lilitan gelung tertutup, dan panjang band diletakkan rata sebelum bergabung. Namakan konvensyen dengan rajah, or give the girth of the pipe or bundle the loop must go round.

Can the same loop be used in a choker hitch?

ya, and a closed loop is the natural form for a choke on pipe, tube and bundles. Sosok tersedak adalah 0.8 of the vertical working load limit, jadi a 5 gelung t tercekik 4 t. Select the width for the arrangement actually used.

Faktor keselamatan manakah yang harus saya pesan, 5:1, 6:1 atau 7:1?

7:1 is the usual European figure for flat woven webbing slings to BS EN 1492-1, 5:1 is the customary North American figure under ASME B30.9, dan 6:1 duduk di antara mereka. Tan yang sama pada faktor yang berbeza ialah artikel yang berbeza dengan lebar yang berbeza, jadi faktor itu terletak pada siasatan.

Bolehkah band itu dicetak dengan rujukan kami sendiri?

ya. Had beban kerja, panjang gelung, faktor keselamatan, batch and your own pack, order or part number can be printed as produced, in the exact string you send, so a band at the far end can be tied back to a line on the packing list.