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5 Options for Dip Tank Maintenance

Posted by Myke Amend on Fri, Oct 23, 2015 @ 04:02 PM

Maintaining the optimum reactive level of form release agents in pipe production dip tanks ensures performance and quality.

By Bob Waterloo

dip-tank-metal-casting-release2Dip tanks play a critical role in the dry-cast pipe production process for many manufacturers. The reactive properties of the fatty acids in the form release agent enable the pipe to smoothly release from the pallet/header. Here’s the problem. The cement/ concrete residue left behind when headers are dipped begins to negate the reactive properties of the fatty acids. Left unchecked, the form release agent eventually begins to lose its effectiveness, pipes will not pull easily from the headers and quality could suffer. The solution: a regular program of monitoring and maintenance that keeps the form release at the optimum reactive release level and reduces replacement and disposal costs.

BENEFITS OF A DIP TANK

Reactive form release agents are the accepted standard in today’s precast and pipe-forming operations. Fatty acids, which are found in an infinite number of blends, are the most commonly used reactive material. Fatty acids have the unique ability to react with the free lime on the surface of the concrete, which results in a nonviolent chemical reaction. This neutralization (or saponification) forms a metallic soap, allowing the product to easily release.

There are a number of benefits to using a dip tank to apply form release during pipe-forming operations, including complete coverage, proper release and reduced chance of operator error. However, a common occurrence when using this method of manufacturing is increasing difficulty with “pulls” or “tip-outs” during stripping over a period of production time. This is generally the result of decreased reactive material in the dip tank as contaminants enter the system and negate some of the reactive material.

MAINTAINING THE DIP TANK

dip-tank-metal-casting-releaseTwo areas must be addressed in the preventive maintenance program for this type of equipment:

  1. Regular maintenance to remove sludge that accumulates in the bottom of the dip tank
  2. Regular maintenance of the release agent’s reactive levels for effective release

The sludge generated in the dip tank includes contaminants from previously dipped headers/joint rings.
These contaminants negate the reactive portion of the form release. As the reactive portion of the release agent gradually decreases, the possibility of concrete sticking to the headers increases, causing a more difficult release. The rate of decrease is gradual and depends on a number of factors, including rate of production and amount of contaminants allowed to enter the dip tank.

REMOVING CONTAMINANTS

Rather than disposing of the entire tank of form release, transfer it to a holding tank and shovel out the sludge. Because the sludge typically contains petroleum hydrocarbons, disposal should be in compliance with local regulations. Then transfer the recovered form release agent back into the dip tank and top it off with fresh release agent.

Remember that by adding fresh release agent to the recovered material, rather than using all new release agent, reactive levels will be reduced and release problems will occur sooner unless the reactive portion is tested and brought back to a normal level. The discoloration of the recovered material from the dip tank is not relevant to the release characteristics, or levels of reactive material.

MAINTAINING REACTIVE RELEASE LEVELS

Maintaining the correct level of reactive agent in the form release is quite simple.

Test the recovered material and bring the reactive portion back to optimum levels. Test a sample from the dip tank (less than one ounce is sufficient) for the reactive level through either titration or infrared analysis. Your release agent supplier should be able to tell you the optimum level of reactive material required, and may be able to run the analysis for you. Once you determine the level of fatty acids, a number of simple calculations determine the amount of pure reactive agent to be added to the dip tank to bring it back to the optimum reactive level.

After adding the recommended amount of reactive material to the dip tank, use an air lance for mixing for a minimum of two minutes, making sure to cover the entire area of the dip tank. Then top off the dip tank with fresh release agent and air lance again for good distribution.

Depending on the amount of contaminants and reduced reactive material, the timeframe between tests will vary. One way to determine the frequency between tests is to establish a baseline. Begin with tests every 30 days, which should be recorded, until a history can be compiled to determine the needed frequency. Normal frequency of adding more reactive ingredients is typically five gallons for every six weeks of normal production.

In many cases, production workers can see the reduced effectiveness of release agents.

It’s important to train them to notify management to add additional reactive material to the dip tank. As usual, science is best, but practical application and analysis are also important.

TOTAL REPLACEMENT OF FORM RELEASE

While removing sludge and maintaining dip tanks by adding new release as needed make sense from an environmental and cost perspective, on occasion you may feel it necessary to clean the entire dip tank to remove all residual sludge and refill the cleaned dip tank with fresh release agent.

COST-EFFECTIVENESS

Dip tank maintenance comes down to five options. Option 1 is the least cost-effective, while Option 5 is the most cost-effective.

 

  • Option 1: Drain the dip tank, dispose of the sludge and old release material, then refill only with fresh form release agent.
  • Option 2: Remove the form release from the dip tank, dispose of the sludge, refill the dip tank with fresh form release, then use the recovered form release to replenish the dip tank as necessary.
  • Option 3: Remove the form release from the dip tank, dispose of the sludge, refill the tank with recovered form release, then top off with fresh form release.
  • Option 4: Remove the form release from dip tank, dispose of the sludge, test the recovered form release, add reactive ingredient to bring it back to an optimum level, then top off with fresh form release.
  • Option 5: If there is not enough sludge to remove but the release is not as good as it should be, test for the reactive level of the release agent in the tank, then add reactive material to return it to an optimum level.
In the long run, a little care and attention to the reactive content level in the dip tank will help to reduce labor costs and maintain or improve casting appearance

Bob Waterloo is technical sales manager, Concrete Release Agents, Hill and Griffith Co., based in Indianapolis

The author has summed up the entire problem and solution of dip tank maintenance in poetic fashion.
To read the poem, please visit precast.org/diptank

Tags: Hill and Griffith, Concrete, Permanent Mold Release Agents

Causes & Fixes for SCC Bug Holes

Posted by Lauren Campbell on Tue, Jul 08, 2014 @ 03:12 PM

By John Pelicone and taken from Precast Inc. Magazine's May/June 2014 issue. 

For full PreCast Magazine Inc. Issue click here

Like a persistent mosquito, one question has plagued precast concrete producers for years: “How can I eliminate bug holes?” In the past, this question was much harder to answer, because concrete was placed at a stiffer consistency that required excessive vibration. And excessive vibration sometimes caused more bug holes. After the introduction of self-consolidating concrete (SCC), bug holes(ii) became a less common occurrence. Yet, as a recent online industry discussion revealed, this perturbing problem is still with us.
Preventing Bug Holes

 

Let’s focus on production’s tail end

The first thing we all learn about SCC is that it’s a tricky devil to work with. There is no room for error, consistency and control are king, and problems, like bug holes, can have more than one cause.

Most online commentators agree that there are three main causes of bug holes:

• Improper selection and application of form release agents

• Problems with SCC mix design (cement, water content, viscosity, admixtures)

• How SCC is placed in the form

Rather than trying to cover all possible sources of bug holes, I decided, like the online commenters, to focus on form work, placement and form release agents. Attempting to cover complex SCC mix-design issues would be too unwieldy for one article(iii).

Two types of release agents

Chemically reactive agents: When a chemically reactive form release agent is used, a nonviolent chemical reaction takes place when fatty acids react with free lime on the surface of fresh concrete. This reaction results in the formation of a metallic soap, a slippery material that allows air bubbles to rise along the vertical surface. This “soapy” film also prevents the hardened concrete from adhering to the forms during stripping.

Barrier release agents: Thicker coatings on forms are typical of the older barrier-type materials, like heavyweight used motor oil, vegetable oils, diesel fuel and kerosene. Barrier type release agents are less expensive than chemically reactive agents, but they are not generally recommended for reducing SCC bug holes.

A problem with the heavier, thicker barrier agents is that the flowing SCC may actually push the release agent down the vertical face of the form, thereby enfolding or entrapping air pockets that lead to surface bug holes.

International input on SCC bug holes

The following is advice from industry experts on bug hole causes and remedies.

Juan Manuel Pereira, Concrete Quality Software, Spain (concrete-quality.com)

“Generally, oils will give the worst finish, especially if applied in excess. Use a wax-based mold-release agent in a thin layer (like polishing furniture), which gives excellent results. They are more expensive, but, when you do the math, the cost per square foot is negligible. Maintaining good form condition is also important.”

Jeff Bishop, precast division manager, Nox-Crete, Nebraska (noxcrete.com)

“Too often, the form release application equipment is inferior, the sprayer has a faulty tip, or the equipment fails to maintain the minimum pump pressure to adequately apply a thin coat on the form surface. Not many plant workers will make frequent stops to check or correct the pressure after they have started spraying. We spent three years developing quality pumping and spraying equipment that ensures a consistent, fine spray.

“Sometimes with truck deliveries, the discharge chute gets ahead of the initial hydraulic head formed by flowing SCC; this can cause entrapped air. You have to make sure you are adding concrete to concrete in such a way that the head is maintained. As the SCC flows down the form and up the side of the form, entrapped air is pushed forward, up and out.”

Cecil Wilson, plant manager, Metromont Corp., South Carolina (metromont.com)

“There are three reasons for SCC bug holes – it’s 1/3 form release agent, 1/3 the mix and 1/3 how the concrete was placed. All three potential causes need to be checked systematically, one at a time, so you can pinpoint the problem. It is imperative to pour SCC so that entrapped air has the opportunity to escape(iv).”

Bob Waterloo, technical sales manager, Hill & Griffith Co., Indiana (hillandgriffith.com)

“Training. I’m a huge proponent of training workers on proper application. ‘Thinner is better’ is what I advise plant workers during my training sessions.

“Here’s an analogy: Think about waxing your car. You put on a thin coat and then buff it out; it’s the same with release agents. In fact, the coating should be thinner than a wax finish on a car.

“But do workers always take the time to mop or rub down forms after spraying? Labor is a major expense for all precasters, and the person prepping forms may not follow proper application methods if he knows the forms are needed in production ASAP.”

John Stewart, global business development manager, Ecoratio, The Release Agent Co., Great Britain (ecoratio.com)

“The main thing is to use a good release agent. Where possible, revert to a top-class release agent rather than a mold oil. This will help surface air escape quickly rather than being retained by a thick oil.”

Alexis Borderon, Reval Stainless Steel & Concrete, Italy (reval-stainless-steel.com)

“We have tried coconut oil, fat, oil-free release agents – all kinds of miracle products from world-class salesmen. I certainly learned that whatever product you use, it must be applied in a thin layer, concrete must be poured close to the form, and never let fresh SCC be poured from a height! We never vibrate.”

Sam Strong, president, Strong Products LLC, Michigan (strongproductsllc.com)

“Release agents generally average $7 to $10 per gallon, but specialized applications may call for a more expensive product. A precaster’s cost and time concerns can result in a poor choice of release agent. A cheaper price may look good but can lead to more labor cost down the road after you have product staining and bug holes. Truth is, product reps rarely see forms being wiped-down or mopped according to manufacturer’s instructions, especially at the smaller precast operations.”


Concrete Form Release

Brian Robinson, continuous improvement manager, Humes Pipeline, New Zealand (humes.co.nz)

“You should try a few different mold release oils – diesel-based, bio oil-based, etc. Suppliers should bust your door down to provide some free samples; stay away from your current so-called ‘cheap’ option. A good release agent that works will end up a similar price – if applied sparingly (correctly), it will result in better quality products. It’s a process of elimination; using different release agents will help you determine if the mix has any issues.

“You’ve got to place from one point in the mold and let it flow. We noticed the SCC places better in the mold using about a 150 mm-diameter opening – not a wide-mouth opening. Also, if the concrete needs to fall a considerable height, a tremie pipe or sleeve works well. This prevents segregation and removal of release agent by falling concrete (which also affects the finish) and reduces bug holes. We never need to mechanically vibrate (we outlaw this) but large, deep tanks may need a small amount of rodding (12 mm-diameter ) reinforcing bar, rodded up and down a dozen times at the opposite side of the mold (from where the concrete is placed) to prevent a discolored seam.”

Greg Stratis, manager, Shea Concrete Products, Massachusetts (sheaconcrete.com)

“We don’t use external vibration for our SCC products – you can quickly over-vibrate the mix. We use SCC on 95% of our product. A lot of our products are vaults with reinforced 3-in. or 6-in. walls. Our SCC design is 5,000 psi with 26-in. spread.

“We are able to get a smooth finish without vibration. In my opinion, if bug holes are present on our product using this mix, it is usually due to too much form oil or a change in our oil consistency. But generally, I would say that the cleanliness of the form and the quality of the release agent used are critical to preventing finish bug holes in the concrete surface.”

Claudio Subacchi, director of R & D, Hawkeye Pedershaab, Iowa (hawkeyepedershaab.com)

“To make sure it is not your release agent, try to make a pour after waxing the surfaces. Sometimes fatty acids (probably the form release agent) generate some bug holes. For wax, we do not use an oil-based one and avoid ones that have beeswax, because they have sugar residues that can potentially cause other kinds of problems. We use a very thin layer of carnauba oil and let it dry, and then cast. If the bug holes go away, then it is your release agent; if not, ask your admixture supplier for a defoaming agent.

“Typically on large architectural surfaces, you do not want to have the SCC travel more than half a meter on a 40 mm-thick pour. If that happens, you may not have bug holes, but you get a shadow from the release agent. See my video for a demonstration(v).”

Todd Leber, chief inspector, Nebco Inc., Lincoln, Nebraska (nebcoinc.com)

“We have had success using two form release agents casting SCC. The key is to apply it as thin as possible. Contact your local distributor to find the right material for your application.”

So in conclusion, let’s summarize the industry’s consensus from for preventing SCC bug holes in three points:

• Use the thinnest application possible of a quality form-release agent, using superior sprayer equipment (pumpers maintained at proper pressure and sprayer tips/nozzles in good condition);

• Maintain proper SCC placement from one pour location in the form, remembering that a slower placement rate allows entrapped air to escape; and

• Maintain forms in clean condition.

John Pelicone

John Pelicone is a private consultant for Big River Industries Inc. and has worked in concrete materials, testing and sales in the precast and prestressed industry for more than 40 years. Contact him at pelicone@bellsouth.net or (770) 682-9896.

Endnotes

ii According to PCA (Portland Cement Association), “The ever-increasing use of structural concrete as an architectural building material has catapulted quality in surface appearance to a prominent position within the concrete construction industry. One of the primary influences affecting the surface aesthetics of concrete is bug holes. Bug holes are surface voids that result from the migration of entrapped air (and to a lesser extent water) to the fresh concrete-form interface. These surface defects manifest themselves mostly in vertical surfaces.”http://www.cement.org

iii See: SCC Part I (characteristics, aggregates and equipment) and Part II (troubleshooting and test methods) in Precast Inc. magazine, January-February and March-April 2014 for detailed information on mix design and control of free water.

iv Best Practices Guidelines for Self-Consolidating Concrete, prepared by the Ready Mixed Concrete Association of Ontario, January 2009, page 10. RMCAO recommends: “For large vertical elements care should be taken not to fill the formwork too rapidly. The placement rate should be slowed to the point that there is sufficient time for the entrapped air to rise to the concrete surface. Since air movement can only take place when the SCC is itself moving into the formwork, slowing the placement rate may assist in removing unwanted air pockets at the formed face of the concrete.”

v See video at: https://www.youtube.com/watch?v=d8luoYe1Fqg Contact Claudio Subacchi of Hawkeye-Pedershaab at: Claudio Subacchi <csubacchi@hawkeye-pipe.com>



learn more about Grifcote products

 

The Hill and Griffith Company is known for our hands on approach. Let us visit your plant and recommend products that suit your needs.

Bulletins and Technical Papers for Metal Casting Products

Tags: Hill and Griffith, Die Casting Release Agents, Concrete, Concrete Form Release Agents, Casting Solutions

New Safety Data Sheet Regulations for Concrete Form Releases

Posted by Lauren Campbell on Mon, May 12, 2014 @ 04:31 PM

The New Globally Harmonized System: The Right to Know

Are you or your employees at risk?

By Bob Waterloo, published in the March/April 2014 issue of PRECAST INC.

New rules, new regulations for concrete form releases. It seems that we are faced with these on an almost daily basis. If you are not up to date, you and your employees could be at risk, and your company could be facing penalties. The United States, in conjunction with other nations, has agreed to new rules regarding employee rights and need to know concerning hazardous materials (previously covered in Material Safety Data Sheets, or MSDSs). The new reference will be called Safety Data Sheets (SDSs).

We use many materials in the precast industry, and many of them have given us better castings – but always at a price. That price often comes in the form of special care and handling of materials that are classified as hazardous, including those that are considered flammable or combustible, or cause irritation, sensitivity, corrosion, and are proven or suspected carcinogens. Part of our responsibility is to help reduce the threat, whether minor or serious, to our workers and the environment. OSHA commonly refers to it as “the right to know.”

You are probably already aware of the new rules and regulations regarding SDSs and the training necessary to comply with the new Globally Harmonized System (GHS). This applies not just to precast suppliers, but the precast producer is also responsible for complying with certain regulations including training.

GHS Label Elements

In making a brief survey of precast and pipe producers, I found that while they are generally somewhat aware, most do not realize the full scope of the new regulations. Here is a quick overview of the GHS.

First, the MSDS is a thing of the past. It is now being replaced by the SDS, and while the format is very similar, there are some significant changes. You will need to have SDSs from all of your suppliers. Some states will have additional requirements, although they are not necessarily addressed here. 

June 1, 2015, is the time for everything to be in place. An additional review of the policies will occur June 1, 2016, after which there may be additional changes. However, some of the laws are already in effect. If you are not in compliance with them yet, you will need to move quickly. 

The Employer is responsible for:  

  • Identifying and maintaining a list of hazardous chemicals known to be present at the plant

  • Obtaining, keeping up to date and providing employee access to SDSs

  • Being sure that all hazardous materials are properly labeled

  • Presenting a training program for all employees who will be exposed to these hazardous materials

  • Having a written hazardous communication program in place

  • Having SDS information available to employees and ensuring they have access to the company training program

  • Ensuring that employees read and understand the SDSs and the label on the containers of all hazardous material

Perhaps the first area of concern to producers is the fact that employee training of the new GHS was to be completed by Dec. 1, 2013. If you haven’t already done so, now is the time to do it. 

Your training program must include:

  • The requirements of the standard

  • Places where hazardous chemicals are present in your work area

  • The location and availability of the written program, the chemical inventory and the SDSs

  • How to access the SDSs in your work area

  • How to read the SDSs

  • How to read the GHS-style container labels

  • Any specific labeling used in-house if different from the standards

  • Specific hazardous chemicals in the employees’ immediate work areas

  • How to detect the presence of a release of a hazardous chemical

  • The physical and health hazards of those chemicals

  • Measures you can use to protect yourself against these hazards

  • Required personal protective equipment (PPE) available and how to use it 

Next, you must have a written program and a list of all SDSs spelled out in the program. All SDSs must be in English (worldwide), and additional languages also must be available to convey to employees in their native language or a language they understand. The manufacturer of the hazardous material is responsible only for supplying the SDS in English, so you are responsible for any additional languages.

Materials that fall under the GHS include: 

  • Health hazards

  • Physical hazards

  • Environmental hazards 

  • Hazards not other classified

  • Other hazardous chemical 

Hazard Warning Levels

Any material falling under the “hazardous” classification must have the following information on the label:

• Product identification
• Pictogram
• Signal word
• Hazard statement(s)
• Precautionary statement(s)
• Name, address and telephone number of the chemical 
manufacturer, importer or other              responsible party 

Hazard Warning Labels

While there is no specific format for the label, all of the above must be clearly shown. Pictograms are also required for quick identification of the hazard. On the SDS itself, there will now be a total of 16 sections – all of which must be completed for any material that falls under the hazardous classification: 

1. Identification

2. Hazard(s)identification

3. Composition/information on ingredients

4. First-aid measures

5. Firefighting measures

6. Accidental release measures

7. Handling and storage

8. Exposure controls/personal protection

9. Physical and chemical properties

10. Stability and reactivity

11. Toxicological information

12. Ecological information

13. Disposal considerations

14. Transport information

15. Regulatory information

16. Other information (including date of preparation or last revision) 

As a final note, all hazardous materials in your workplace must be cross-referenced by supplier and/or manufacturer.

These new OSHA regulations place an additional burden not only on the manufacturer/distributor, but also on the end user– you! Owners and operators are now responsible for keeping employees aware of any hazardous material on the premises, and all new employees must go through this training before being allowed in the workplace. OSHA will likely ask about the GHS in your workplace and assess stiff fines for not being in compliance.

The National Precast Concrete Association offers its members a free webinar titled “Webinar: Guide to Globally Harmonized System Documentation” by logging on to precast.org/ education.
Concrete Form Release SDS paper 3-14 

Bob Waterloo is Technical Sales Manager, Concrete Release Agents, Hill and Griffith Co., based in Cincinnati. For additional information, contact him at bwaterloo@hillandgriffith.com

The online Precast Inc. magazine article is available at: precast.org/2014/03/new-globally-harmonized-system-right-know/.

For a PDF of this article, click here or on the image.


learn more about Grifcote products

 

The Hill and Griffith Company is known for our hands on approach. Let us visit your plant and recommend products that suit your needs.

Bulletins and Technical Papers for Metal Casting Products

Tags: Hill and Griffith, Concrete, Concrete Form Release Agents, Casting Solutions

STRONGER GROWTH AFTER WINTER ENDS

Posted by Samantha Farris on Thu, Apr 03, 2014 @ 12:00 PM

Mixed Data Point To Stronger Growth When Winter Weather Ends

Reuters
(3/26) reports that positive data on consumer confidence and housing prices on
Tuesday was offset by a drop in new home sales. Still, Reuters says that the
economy is poised for stronger growth once the harsh winter ends. Looking at
the reports, the Conference Board reported that its index of consumer attitudes
rose to 82.3 in March from 78.3 in February, notching its highest reading since
January 2008. That number is well above the 78.6 expected by economists. Bloomberg
News
(3/26, Peralta) says that the rise in consumer confidence was
“propelled by improved optimism about the economy’s prospects, signaling growth
will strengthen after a weather-related slowdown.”

Bloomberg News (3/26, Stilwell) reports that housing prices “climbed at a slower pace
in the year through January... indicating momentum in the housing market may be
cooling.” Still, the S&P/Case-Shiller index of housing prices in 20 major
metropolitan areas rose 13.2 percent this January over January 2013. Economists
expected a 13.3 percent increase. January’s prices were up 0.8 percent over
December.

The WallStreet Journal (3/26, House, Subscription Publication) reports that
Commerce Department data shows the sales of new homes fell 3.3 percent in
February to a seasonally adjusted annual rate of 440,000 units. That’s below
the 445,000 rate expected by economists. In addition, January’s originally
reported strong increase was revised downward. The Journal says that the data
is a sign that harsh weather and rising mortgage rates impacted the housing
recovery in recent months.

 Published by:

North American Die Casting Association Weekly Update

 

 

 

 
 

Tags: Hill and Griffith, Concrete, Biodegradable Concrete Form Release

Precast Show

Posted by Samantha Farris on Thu, Jan 30, 2014 @ 01:28 PM

describe the image

 

Come visit Booth 945. The Hill and Griffith Company offers the Perfect Release with Grifcote concrete form release agents that are readily and inherently biodegradable.

The Precast Show 2014 is in Houston, TX.  February 13th through February 15th.

 

http://precast.org/theprecastshow/

 

 

Tags: Hill and Griffith, Concrete, Concrete Form Release Agents

2013 OPCA Annual Conference and Tradeshow

Posted by Samantha Farris on Fri, May 10, 2013 @ 02:08 PM

Mike Lawry and Tom Dempsey attended the 2013 Ohio Precast Concrete Association Annual Conference and Tradeshow. H&G continues to support the Precast and Prestressed Industries in state and national levels.Picture

Tags: Concrete, Conference, Tradeshow, OPCA, Ohio Precast Concrete Association