One Way Webbing Sling

الف زنجیر بافته یک طرفه 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 حلقه بی پایان form — the shape specified for pipe, tube and bundling work, because a loop wraps a cylinder instead of hooking it. محدوده استاندارد: 1 تی به 12 تی, band width 25 میلی متر به 300 میلی متر, فاکتور ایمنی 5:1, 6:1 یا 7:1, loop length 0.5 متر به 100 متر, marked to BS EN 1492-1.

What “one way” decides, and what it does not

The phrase describes the commercial life of the article, not its quality. A one way sling is manufactured, اثبات بارگذاری شده است, 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. هست issued with the load, so it becomes a line on the packing list rather than an item in a sling register. هست inspected once, at the point of issue, while a fault can still be replaced from the same consignment. And its print is its whole record: محدودیت بار کاری, طول, 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; این یک حاشیه بدون رتبه است که از آسانسور خارج شده است. 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 زنجیر تخت بی پایان تک لایه 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. عرض یک انتخاب آزاد نیست: it follows from the working load limit and from the safety factor, so the same tonnage appears at three widths. طول حلقه, لایه بندی, 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. را محدودیت بار کاری 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. را عرض then comes from the surface being wrapped: a coated pipe and a painted machine at the same tonnage do not want the same band.

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

یک حلقه انتهایی برای اندازه گیری بین آنها ندارد, 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, بدون باند دوم برای تعویض.

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.

چوک آرایشی است که یک حلقه برای آن خریداری می شود, و همچنین آن چیزی است که هزینه دارد 20 % of the printed figure. الف 4.5 دسته لوله تی خفه شده است 5 حلقه t یک اضافه بار است, not a margin — the answer is the next width up, not a longer band.

Coating and surface compatibility

علامت گذاری, 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: محدودیت بار کاری, the loop length with its convention, عامل ایمنی, and the reference the despatch actually uses — a batch, یک شماره بسته, شماره سفارش یا شماره قطعه خودتان. That reference is what ties the band on a quay to the line on a packing list in an office.

• خوانا بعد از سفر, نه بعد از تولید. Small, low contrast print on a face that enters the choke will not be read at the far end.
• Colour as a second channel. یک رنگ در هر نوع بسته, 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, and the bands can be packed inside a crate, به تسمه ای چسبانده شده یا به یک بسته چسبانده شده است, برچسب گذاری شده در هر بسته.

The single inspection, and what it looks at

A one trip band is checked once, مورد بحث, while a fault can still be replaced from the same consignment. Look at four things, به این ترتیب: بافت در جایی که به بار می رسد (برش می دهد, سایش, صورت لعاب دار یا نیشگون), اتصال جایی که حلقه بسته می شود, the label — an unreadable figure cannot be matched to the pack it was cut for — and what the band has been lying in. شن, دسته جمعی, روغن و آب ایستاده به محل تماس می روند, and a clean band is the cheapest protection available.

Protect the band from sharp edges, سطوح داغ و پاشش جوش با آستین یا محافظ بالشتکی. بالا 100 درجه سانتی گراد, or where sparks are present, polyester is the wrong fibre and an زنجیر گرد بی پایان 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, no inspection register, no repair and no loss write-off — but it has to be counted correctly, because nothing comes back to cover a shortfall. از بسته بشمار, نه از تناژ: دو انتخاب در هر بسته دو باند است, a four point lift is four, ninety packs at two picks is 180 باندها. Add two to five per cent for the band cut while the pack is made up, بنابراین کسری به جای تاخیر در حوض، به یک خط سفارش تبدیل می شود.

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, الف توری بالابر بار is the article to price against it. The form with eyes at both ends, for loads that are hooked rather than wrapped, is on the زنجیر یک طرفه یکبار مصرف صفحه; the wider family is on the تسمه های یکبار مصرف و single use lifting slings endless loop pages.

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, choked or basket, 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.

سوالات متداول

What is a one way webbing sling?

A rated polyester webbing sling supplied for a single journey. با بار حرکت می کند, 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?

خیر. فیبر, بافتن, عرض, فاکتور ایمنی, working load limit and marking are specified exactly as for a returnable sling. این کلمه سفر را توصیف می کند, 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. عرض معیار حفاظتی است: هر چه باند پهن تر باشد, 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: محیط حلقه بسته, و طول باند قبل از اتصال صاف شد. Name the convention with the figure, or give the girth of the pipe or bundle the loop must go round.

Can the same loop be used in a choker hitch?

بله, and a closed loop is the natural form for a choke on pipe, tube and bundles. رقم خفه شده است 0.8 of the vertical working load limit, بنابراین یک 5 چوک های حلقه t 4 تی. Select the width for the arrangement actually used.

کدام فاکتور ایمنی را باید سفارش دهم, 5:1, 6:1 یا 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, و 6:1 بین آنها می نشیند. تناژ یکسان در یک فاکتور متفاوت، یک کالای متفاوت با عرض متفاوت است, so the factor belongs on the enquiry.

Can the band be printed with our own reference?

بله. محدودیت بار کاری, loop length, فاکتور ایمنی, 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.