It is currently Sat Nov 25, 2017 12:03 am

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 22 posts ]  Go to page 1, 2  Next
Author Message
 Post subject: Your thoughts on this type of blasting medium?
PostPosted: Fri Dec 04, 2015 11:03 am 

Joined: Thu Oct 21, 2004 7:24 am
Posts: 478
Location: Canada
Undoubtably quicker than a needle gun or a scraper, but safer than sandblasting?
for those of you who can't get the article to work, it involves using high pressure water and garnet dust to blast off industrial coatings. It is currently being used on Santa Fe 2912. I know that sandblasting locomotives in frowned upon due to the abrasive medium getting into every nook and cranny and rendering bearing surfaces unusable later, can this be much different?
http://www.chieftain.com/business/40035 ... ter-museum


Offline
 Profile  
 
 Post subject: Re: Your thoughts on this type of blasting medium?
PostPosted: Fri Dec 04, 2015 11:12 am 

Joined: Tue Sep 22, 2015 12:36 pm
Posts: 178
You are still using an abrasive although handled by a different carrying media, water instead of air and then you add moisture to the mix to cause flash rust.

I have used sand blasting with success on carburetors and engine blocks but meticulous cleaning is required afterwards, as well as complete dissasembly of the item in question.

Dry Ice blasting is much safer although costly.

_________________
"What smells like Lube Oil and Diesel? Oh It's just my Locomotive Breath"


Offline
 Profile  
 
 Post subject: Re: Your thoughts on this type of blasting medium?
PostPosted: Fri Dec 04, 2015 11:15 am 

Joined: Tue Sep 14, 2004 7:52 am
Posts: 1241
Location: Strasburg, PA
Garnet is defined as a silicate abrasive, so I would assume that this technique would leave grit in the machinery the same as sand blasting. I gather that the water mist cuts down on the dust cloud while blasting is going on.

_________________
"It was not easy to convince Allnutt. All his shop training had given him a profound prejudice against inexact work, experimental work, hit-or-miss work."
C. S. Forester

Strasburg Rail Road Mechanical Department


Offline
 Profile  
 
 Post subject: Re: Your thoughts on this type of blasting medium?
PostPosted: Fri Dec 04, 2015 12:46 pm 

Joined: Tue Mar 10, 2015 10:29 am
Posts: 45
Location: Michigan
The process has been used in the Electrical Apparatus Repair Industry for many years.

Cleaning dirt, debris from an item without creating other problematic factors.
(Residual moisture causing electrical faults, a pile of medium to clean-up, etc.)

It's somewhat of a "band-aid" approach if you really dive into the process.
Yet, it eliminates having to completely dismantle an item to clean/repair/restore it.

If you choose such an ambition, have a willing participant to perform the task,
and have no expectations for the result.
You could be awe-surprised or disappointed with the results.

"Garnet" is indeed abrasive.
It's popular in electrical repair because it does not leave conducting electrical properties on the item being machined, cleaned, etc.

Nothing like being SIDE TRACKED!
I logged on to the forum to reply to the locomotive cab red roof "thang". Ha ; )

Always enjoying the banter, wisdom, heated drama, and intellectual armchair entertainment.

Some of you should run for office!

(snickering~~~ just kidding ; )

John


Offline
 Profile  
 
 Post subject: Re: Your thoughts on this type of blasting medium?
PostPosted: Fri Dec 04, 2015 8:24 pm 

Joined: Sun Aug 22, 2004 3:37 pm
Posts: 1058
Location: Pacific, MO
I wonder how many engines are basically dead in the water because someone sandblasted them? SP 4460 comes to mind.

1522 got sandblasted while all the drivers, etc were out of her. I never did think that was a good idea and still don't. We didn't have any issues, but I'll bet you could still find some sand in nooks on her.


Offline
 Profile  
 
 Post subject: Re: Your thoughts on this type of blasting medium?
PostPosted: Fri Dec 04, 2015 9:10 pm 

Joined: Fri Mar 26, 2010 11:43 am
Posts: 426
Location: Floyd, AR
Garnet is a coal slag abrasive, typically. Called black beauty or black diamond or black lightning or whatever corny name the particular bagging plant comes up with. It works quite well to cut off rust and crud. It's supposed to be a LOT safer to your lungs then sand based abrasive. It can make a pretty fine surface finish. The particles feel sharp, much sharper then sand. I've never used it with the pressure washer tho, so I don't know how it works compared to air. I would expect it to get in all the same places as dry blasting.

_________________
Robert Longhofer,
Board Member, Cotton Belt Rail Historical Society, Arkansas Railroad Museum, steam engine SSW819.
Any information or opinions I express are my own, and are not the views of the CBRHS or anyone else, unless explicitly stated otherwise.


Offline
 Profile  
 
 Post subject: Re: Your thoughts on this type of blasting medium?
PostPosted: Fri Dec 04, 2015 11:51 pm 

Joined: Wed Jan 15, 2014 9:14 am
Posts: 174
This sounds like a similar technique to what was used on an SW1200 for a local shortline. The painting contractor had a couple totes (250 gal?) In their trailer with a special water (softened, maybe de-ionized) and they injected a rust inhibitor into the stream. The company was out of Ohio but traveled all over the US and specialized in locomotives and rail cars. They did an incredible job on the SW1200, and I think it took less than a week and included paint and vinyl graphics. Looked great and I believe they put a clear on her. Look up MMRR 1216. They even repainted inside the cab and everything under the hood, and I'm not talking slapping some paint on. It looked good inside too. I can't find the contractors card though.


Offline
 Profile  
 
 Post subject: Re: Your thoughts on this type of blasting medium?
PostPosted: Sat Dec 05, 2015 6:17 am 

Joined: Thu Apr 14, 2005 9:34 pm
Posts: 1888
Location: Copenhagen, Denmark
Ugh. Things to complain about:

- they are blasting directly on the pin bearing surfaces, which are unprotected

- the drivers are out of alignment (is that the right word?), which means the engine was moved here after rods were removed, and will be moved again to final (nothing is ever final) display location.

-all the concerns about grit in bearings are valid here

Is it really that important to scrape all these heavy metal items clean? Especially in their climate, a cosmetic color touch up is all they need.

_________________
Steven Harrod
Lektor
Danmarks Tekniske Universitet
Institut for Systemer, Produktion, og Ledelse


Offline
 Profile  
 
 Post subject: Re: Your thoughts on this type of blasting medium?
PostPosted: Sat Dec 05, 2015 7:21 am 

Joined: Fri Mar 04, 2005 5:29 pm
Posts: 256
Location: Three Bridges NJ
I just had PRR 9206 blasted with Garnet, check out facebook for photos. https://www.facebook.com/LV-112-PRR-9206-110178065671517/

Garnet is lava rock and the product that my contractor used came from New Zealand. It is a little more money than other blasting media, but it was worth it. The dust was practically non-existent, and left a fine finish.

I too was skeptical about getting grit in places I did not want. I spoke to my contractor about my concerns and he gave me some advice as to prep prior to blasting. So I gorilla tapped taped over the traction motor vents and then tarped the whole truck. In the engine room I used heavy duty contractor leaf bags and bagged everything. The air cleaner, aux gen, main gen, governor, load regulator, air pup intake filers, bearings on the accessory shaft, ect. I then tarped everything that I had just bagged, the tarps covered essentially everything under the hood. I also bagged and tarped the cooling fans and tapped any holes to the engine room that I saw.

In the end, I spent about $200 bucks on tarps, tape and bungee cords and was quite pleased when I pulled the bags off. Some dust made it to the floor of the engine room, but noting on anything that was bagged and tarped.

Now as far as media blasting a steam engine that will be used in service is certainly another kettle of fish, and not real sure I would do that. My only concern with what these guys are doing is that I don’t see any dust masks……………..

Scott


Offline
 Profile  
 
 Post subject: Re: Your thoughts on this type of blasting medium?
PostPosted: Sat Dec 05, 2015 7:27 am 

Joined: Sun Aug 22, 2004 8:31 am
Posts: 1102
Location: South Carolina
I'm not sure how effective it is from an abrasive standpoint, but the ideal blasting media from a cleanup standpoint is dry ice:

http://www.coldjet.com/en/information/w ... asting.php

The media disappears almost on contact so there's nothing to clean up or ruin the machinery.

_________________
Hugh Odom
The Ultimate Steam Page
http://www.trainweb.org/tusp


Offline
 Profile  
 
 Post subject: Re: Your thoughts on this type of blasting medium?
PostPosted: Sat Dec 05, 2015 9:49 am 

Joined: Sat Aug 28, 2004 11:22 am
Posts: 80
Location: Northeast Pa.
We used it at my last job, but we had 40'000 psi water blasters and used it to cut doorways into the sides of oil tanks in refineries to clean out and inspect.


Offline
 Profile  
 
 Post subject: Re: Your thoughts on this type of blasting medium?
PostPosted: Sun Dec 06, 2015 7:22 am 

Joined: Fri Mar 04, 2005 5:29 pm
Posts: 256
Location: Three Bridges NJ
I tried CO2 blasting first, and while it took off the paint, it was very slow. It would have taken more than a week to blast the loco at very significant costs. CO2 is down low on the abrasive scale around 2.5, Garnet is up around 6-7 depending on the coarseness of material. I counted at least 8 layers of paint that had to be removed, it was pretty darn thick!

On a side note, we made a couple of bridge plates and sprinkled the left over Garnet into the wet paint and brushed it out. The fineness of the Garnet worked way better than plain sand. It’s been 3 weekend of heavy duty Christmas train foot traffic with no obvious signs of wear.

Scott


Offline
 Profile  
 
 Post subject: Re: Your thoughts on this type of blasting medium?
PostPosted: Sun Dec 06, 2015 4:19 pm 

Joined: Thu Nov 22, 2007 5:46 am
Posts: 2447
Location: S.F. Bay Area
whodom wrote:
the ideal blasting media from a cleanup standpoint is dry ice: The media disappears almost on contact so there's nothing to clean up or ruin the machinery.

Common misconception. Consider this: Why are you blasting? Because there's a coating you want to remove, and you are doing so by chipping and pulverizing it. So even with an ideal blast media (electrons?), you still have a great cloud of old paint, dirt, rust and mill scale. Not fun.


Offline
 Profile  
 
 Post subject: Re: Your thoughts on this type of blasting medium?
PostPosted: Mon Dec 07, 2015 11:46 am 

Joined: Fri May 28, 2010 9:52 am
Posts: 83
We’ve had excellent results with grit wet-blast applications. Like everything, it takes a little thought, planning, and practice. Once prepped, two people can wet blast the side of a typical freight car to bare metal in one day without dust and inhalation issues associated with conventional sand blast technique. The media is typically readily available, inexpensive, and can be recycled. The following notes are provided for consideration.

Blasting grit (Black Beauty®) is available in four grades: medium, fine, extra fine, and elite. The material is processed boiler slag. After shopping around, we purchased a pallet of 100-pound bags (32-34 bags) for about $250 plus tax. With recycling, this supply lasted 2-3 seasons. The following link provides typical MSDS info for a suitable product:

http://flatrockbagging.com/info/Abrasiv ... 0Specs.pdf

Ideally, sufficient space should be available around the car being prepped; however, we worked with coupled equipment. Car / site preparation consists of covering the ground, trucks, neighboring cars and related equipment with 6-mil plastic sheeting to protect sensitive areas – plan bearing trucks are covered / wrapped with two or move small sheets to assure adequate protection, but we found there is no need to go overboard. Sheeting is typically available in 20’ x 100’ rolls from better super-box or builder supplies and can be cut to size, dried, folded and reused.

Plastic sheeting should be arranged to capture spent grit yet allow sufficient drainage. We typically placed 2x4s near the perimeter of our work area to create a small berm before deploying plastic sheeting – small spaces between 2x4s are allowed, as needed, to permit water runoff. We also used bricks etc to secure sheeting on breezy days. Spent grit typically falls out / accumulates adjacent to the work area, it does not transport well. With our equipment, water runoff is less than 4 gallons per minute – a permeable soil beyond the work area should allow sufficient infiltration. After a work session, spent grit (slop) is collected, dried, and recycled, but more on that later.

Once plastic sheeting is in place, we deployed scaffolding to allow sufficient access and freedom of movement. We use only one section of 3-foot wide scaffolding equipped with screw-jack, roller or solid base plate depending on job needs. A 3-foot wide set is OSHA legal to 12-feet above grade (height = 4 times width), which is sufficient in most applications and also allows adequate clearance between adjacent tracks, if needed. Outriggers and top railings are also available to assist worker safer during roof / top of car work, etc. As I recall, our rig costed $900, but it is priceless and has provided years of service. A step ladder is used to gain access to work platforms. After a work session, equipment is washed down, planking stood-up within the frame and allowed to dry over night before being stowed.

We learned blast technique from a welder friend – who also kindly loaned his gun to us during the first season. I since purchased a Suttner Model ST-55 wet blast gun with 4 gpm venture (orifice) – www.suttner.com. The smaller orifice size works well, but doesn’t use a ton of water or high pressure – the ST-55 is rated for 3600 psi, easily attained with a pressure washer. Blast guns can also be rented from better builder supplies, industrial shops, etc., but they are typically not well maintained and make for timely delays. I found that grit will erode the plastic line that comes with the gun at least once a season, but it’s an easy repair.

It’s also necessary to keep grit dry during work activities. We put grit in plastic, 5-gallon buckets on the work platform (one 100# bag fills 2 ½ buckets), cover each bucket with a black trash bag, and then penetrated the bag with the gun’s lance. As long as we were careful with over spray, we had no problem with clogging by damp grit…most of the time.

We use a Craftsman, 3400 psi, 4 gpm, pressure washer to power the operation. The washer and gun must be connected using high pressure hose with suitable high pressure fittings – not standard air fittings. After renting a washer for a couple work sessions, we bought one of our own. Water is supplied via a garden hose. We built a Y-shaped hose tap to supply the pressure washer as well as a separate hose and nozzle, which hung on the scaffolding to tidy-up the work area, freshly blasted metal and the worker. We also built a cut-off valve for our supply line, a useful item if supply shutoff is far away from the work site.

We blasted our equipment during warmer months wearing suitable work clothing and face shield – eye and ear protection is a must. We typically set-up equipment Friday afternoon, blasted and cleaned-up Saturday and painted Sunday. Grit blasting produces a grey metal surface suitable from treatment / priming after drying overnight. A slight hazy may form on fresh surfaces, but for the most part, car sides remained very suitable for treatment / coating. Blasting technique is good for large areas as well as spot blasting localized corrosion prior to coating – shooting an entire car to bear metal may be overkill. At the end of a blast session, spent grit is scooped into 5-gallon plastic containers, moved to homemade driers and spread-out on plastic sheeting.

We arranged a drying area – 4x8 plywood sheets covered with plastic sheeting - under a nearby car. Once dried – a week or two – grit can be recycled. We found grit could be reused 4-5 times before grains were too rounded to be effect. Grit can be stored in resealable, 55-gallon drums lined with two drum-size plastic liners. Surface paint testing is needed to avoid issues with leaded coatings otherwise exhausted grit is disposed as a residual waste without complications.

Each tool has its good points and bad. Grit blasting is safe and convenient means for surface prep. It produces no dust - no unhappy neighbors. It’s a fast way to clean large areas and gets into all nooks and crannies that needles or grinders can’t reach. It allows two guys to clean one car, e.g. a rusty caboose, working at a leisurely pace in five weekend work sessions. It sure beats working on the side of a metal car on a hot summer day with needle gun or power brush. Cost will vary depending on equipment / supply availability, etc.

Again, these ideas are offered for consideration. Nothing is set in stone.

Thanks for the opportunity to share,

Jim K


Offline
 Profile  
 
 Post subject: Re: Your thoughts on this type of blasting medium?
PostPosted: Tue Dec 08, 2015 12:15 am 

Joined: Thu Dec 12, 2013 1:26 pm
Posts: 44
What about lead abatement?


Offline
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 22 posts ]  Go to page 1, 2  Next

All times are UTC - 5 hours [ DST ]


 Who is online

Users browsing this forum: Bing [Bot], Google [Bot], sbhunterca, Yahoo [Bot] and 54 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to: