檢視單個文章
舊 2012-09-08, 20:47   #1
大濟
攀言癌症患者
 
註冊日期: 1999-11
住址: Madison
文章: 689
大濟 是普普通通的會員
龍洞 "De"-bolt 的方法

”Rebolt" -- 大夥能一起努力把龍洞的老舊 bolt 換新,這是件好事。但是如何 rebolt?如何讓大夥的熱情、花費的心力更持久、更有意義?

簡單的打掉舊 bolt 突出岩壁的部份(耳片),留在岩壁裡面的 bolt 就不管了,任其腐朽,然後在旁邊再鑽一個新洞,放上一個新的 bolt?

這樣的 rebolt,一條路線原來需要鑽10個洞,rebolt 以後變成20個洞,再10年後如果又要 rebolt,變成30個洞?如果毫無節制,這樣下去,龍洞能承受多久?當您我這一代在享受 rebolt 結果 -- 安全的攀登 -- 同時卻裝作沒看到 rebolt 後那些留在那裡默默無言的舊洞的時候,我們留給下一代的是什麼?

有沒有比較好的方法?即使這些方法可能需要多一點的心力?

以下兩篇短文(等待有心人翻譯),第一篇敘述用一些比較不同的器具可將 Petzl P38 (現在龍洞老舊 bolt 的型號)“拉” 出、或將原來的洞 “擴孔” 將 Petzl P38 取出,這樣就可以用原來的洞放置新的 bolt,不需再鑽新洞 -- “De"bolt!第二篇則討論為什麼海邊的 bolt 特別容易鏽蝕,並介紹比較適用的 bolt。

這些資料、作法、意見不見得適用龍洞,但總是一些不同的作法,總是可以讓我們思考一些新的、不同的開始,儘供參考。

-------------------------------------------------------------------
(以下短文敘述如何將 Petzl P38 拔出、擴孔,摘錄自:http://www.rockclimbing.com/cgi-bin/...i?post=2309733)

We've been there! In the softer limestone in the Frankenjura they (P38) come loose anyway and you can rip them quite easily, for this reason they are not recommended and are being replaced.

In the hard limestone you can still usually pull them as the holes were probably not as perfectly drilled as they should have been and water has eroded the rock away as well but you need a fairly strong puller for this.

Drilling the pin out is a hopeless task, a friend has done this and it took 3 cobalt steel drill bits and 2 batteries on a Hilti.

We replaced some last year in granite by first trying to pull them with a “hydraulic puller”(見圖左一), about 50% came out this way. The ones that broke (the hanger) we chopped with an “angle grinder”(簡圖左二) and then cored them out with a “diamond core drill”(見圖左三、左四), about 4 minutes and 6 to a battery.

The hole left is nearly 14mm but has to be deepened and we either use a 12mm or 16mm glue-in depending on what we feel like, there is no advantage either way.

As far as I know the (P38's) body is a machining grade of 316 and the pin something else a bit harder which I've forgotten! They are cheap (being remaindered) at the moment probably because they are unpopular and they don´t conform to the newer version of the UIAA Safety Label.



-------------------------------------------------------------------------------
(以下短文討論海邊 bolt 易鏽蝕原因以及建議使用的 bolt,摘錄自:http://www.safeclimbing.org/education/deepbluesea.htm)

The Devil and the Deep Blue Sea: New Warnings about Sea Cliff Bolts
By John Byrnes, Skip Harper and Mike Shelton

With the growth of sea-side climbing around the world there has been an ever increasing number of bolt failures. The marine environment is tough on metals. The constant exposure to salt water promotes a specific powerful corrosion mechanism that is not seen at inland climbing areas. High quality stainless steel bolts and hangers have failed in as little as 18 months when placed near the sea. Most of the time there is no visible indication they are unsafe. They may look fine but not hold body weight, much less a fall. Affected cliffs don't even need to be right over the water. Breaking waves create a fine mist which can be transported inland for miles by the wind.

The stainless steels used today in almost all climbing bolts are susceptible to a failure mechanism called Chloride Stress Corrosion Cracking or SCC. Just like it sounds, the chlorine ion, which results from dissolving salt in water, and stress must both be present. A typical multi-piece expansion bolt has the shaft in tension, and the hanger has complex stresses placed on it when it is clamped against the rock as you tighten the nut. This type of bolt placed in a sea cliff is a bomb with a short fuse. Once started, SCC spreads like a disease following the stress lines in the steel, much like grass grows in small cracks in concrete and forces the pieces apart. The cracks get larger over time, and soon the microscopic grains of the metal are no longer in contact.

Although SCC can occur on any part of a bolt exposed to salt water, it usually occurs under the hanger where salt water wicks into the crevice between the hanger and the rock surface. Bolts corroded by SCC typically break flush with the surface of the rock. Hangers typically break at the ninety-degree bend, and nuts can crack just about anywhere. At least one bolt vendor sells stainless steel "clad" bolts and nuts. These have a thin outer cladding of stainless steels urrounding a core of mild steel. This type of bolt seems to be worse then others, since once SCC cracks the cladding,oxidation (rust) finishes the job in short order. If you see a stainless bolt with a rust "beard" on the rock under it, beware!

THE TORTUGA (Turtle)

We wanted a bolt that could be trusted for over 30 years in this environment. But what material to use? We still couldn't ignore the more common corrosion mechanisms such as oxidation, galvanic and chemical corrosion.

• Oxidation (rust) is accelerated by water, salt and warm temperatures.

• Galvanic corrosion occurs when two dissimilar metals are in contact in the presence of an electrolyte. Salt water is an excellent electrolyte.
Multi-piece bolts always have some potential for galvanic corrosion since it's almost impossible for the shaft, sleeves, nut and hanger to be perfectly matched.

• Chemical corrosion could take place if there is some unusual compound present in the rock that could attack the bolt. It's common for limestone to have a wide variety of compounds embedded in it.


So when we considered these other corrosion mechanisms in addition to SCC we realized that we needed a one-piece glue-in design made of something besides steel. There were several possible materials we could use, but we needed a marriage of material, costs and supplier.

Titanium was our first choice and after being turned away by several climbing equipment manufacturers we hooked up with Ushba Mountaineering. After our first meeting at the local pub, and several beers, we were sure this marriage was going to last.

We went through a meticulous design process before boiling it all down to the simplest solution. The new Ushba "Tortuga" bolts (Spanish for turtle) are simple "P" shaped welded cold-shuts made out of titanium. They are large enough to be used for both intermediate bolts and lowering anchors. They meet all existing UIAA standards for strength and willset new standards for anti-corrosion properties. (The UIAA has formed a special sub-committee to investigate marine bolt standards.)

We also had to think about the glue since the glue provides an important part of the overall solution. The glue isolates the bolt from any possible metals or chemical corrosives embedded in the rock and prevents water from wicking into small crevices next to the metal. It also has to withstand the marine environment in its own right! Here we gleefully took Sam Lightner's advice gained from years of gluing bolts in Thailand. The Hilti HIT C-100 appears to be your best bet.

So if you're putting up a sport route near the ocean, use the right stuff and put up a safe route that people will enjoy for years to come. If we do it right, climbing in Paradise is within our reach.
上傳的縮圖
點一下圖片以檢視大圖

名稱:	Hydraulic Puller.jpg
檢視次數:	1526
檔案大小:	5.7 KB
ID:	1663  點一下圖片以檢視大圖

名稱:	Angle Grinder.jpg
檢視次數:	1452
檔案大小:	9.2 KB
ID:	1664  點一下圖片以檢視大圖

名稱:	Diamond Core Drill_1.jpg
檢視次數:	1435
檔案大小:	5.7 KB
ID:	1665  點一下圖片以檢視大圖

名稱:	Diamond Core Drill_2.jpg
檢視次數:	1560
檔案大小:	7.0 KB
ID:	1666  

此文章於 2012-09-18 20:41 被 大濟 編輯.
大濟 目前離線   回覆時引用此篇文章