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Abstract

The U.S. Environmental Protection Agency (EPA) has funded

a pilot project to assist small and medium-size manufacturers

who want to minimize their generation of waste but who lack

the expertise to do so. In an effort to assist these manufacturers Waste Minimization Assessment Centers (WMACs) were

established at selected universities and procedures were

adapted from the EPA Waste Minimization Opportunity Assessment Manual (EPA/625/7-88/003, July 1988). That document has been superseded by the Facility Pollution Prevention

Guide (EPA/600/R-92/088, May 1992). The WMAC team at

the University of Tennessee performed an assessment at a

plant that manufactures stainless steel pipes and fittings. In

order to fabricate the pipes, stainless steel coil stock is processed in tube mills to form continuous, cylindrical pipe. Seams

are welded and the pipe is cut to specified lengths. The pipes

are hardened in annealing furnaces and quenched. Then the

pipe ends are deburred and straightening is done as required.

The final step is acid pickling for cleaning and etching of the

pipes. The team’s report, detailing findings and recommendations, indicated that the onsite treatment of pickling rinse water

generates a large quantity of hazardous sludge and that significant cost savings could be realized by installing a sludge

drying oven to reduce the volume and weight of sludge shipped

offsite.

This Research Brief was developed by the principal investigators and EPA’s National Risk Management Research Laboratory, Cincinnati, OH, to announce key findings of an ongoing

research project that is fully documented in separate report of

the same title available from University City Science Center.

Introduction

The amount of waste generated by industrial plants has become an increasingly costly problem for manufacturers and an

additional stress on the environment. One solution to the

problem of waste generation is to reduce or eliminate the

waste at its source.

University City Science Center (Philadelphia, PA) has begun a

pilot project to assist small and medium-size manufacturers

who want to minimize their generation of waste but who lack

the in-house expertise to do so. Under agreement with EPA’s

National Risk Management Research Laboratory, the Science

Center has established three WMACs. This assessment was

done by engineering faculty and students at the University of

Tennessee’s WMAC. The assessment teams have considerable direct experience with process operations in manufacturing plants and also have the knowledge and skills needed to

minimize waste generation.

The pollution prevention opportunity assessments are done for

small and medium-size manufacturers at no out-of-pocket cost

to the client. To qualify for the assessment, each client must

fall within Standard Industrial Classification Code 20-39, have

gross annual sales not exceeding $75 million, employ no more

than 500 persons, and lack in-house expertise in pollution

prevention.

The potential benefits of the pilot project include minimization

of the amount of waste generated by manufacturers, and

reduction of waste treatment and disposal costs for participating plants. In addition, the project provides valuable experience for graduate and undergraduate students who participate

in the program, and a cleaner environment without more regulations and higher costs for manufacturers.

Pollution Prevention Assessment for a Manufacturer of

Stainless Steel Pipes and Fittings

ENVIRONMENTAL

RESEARCH BRIEF

Richard J. Jendrucko*, Julia A. Myers*, Todd M. Thomas*, and

Gwen P. Looby**

 *University of Tennessee, Department of Engineering Science and Mechanics.

 **University City Science Center, Philadelphia, PA.

United States

Environmental Protection

Agency

National Risk Management

Research Laboratory

Cincinnati, OH 45268

Research and Development EPA/600/S-95/017 August 1995
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Methodology of Assessments

The pollution prevention assessments require several site visits to each client served. In general, the WMACs follow the

procedures outlined in the EPA Waste Minimization Opportunity Assessment Manual (EPA/625/7-88/003, July 1988). The

WMAC staff locate the sources of waste in the plant and

identify the current disposal or treatment methods and their

associated costs. They then identify and analyze a variety of

ways to reduce or eliminate the waste. Specific measures to

achieve that goal are recommended and the essential supporting technological and economic information is developed. Finally, a confidential report that details the WMAC’s findings

and recommendations (including cost savings, implementation

costs, and payback times) is prepared for each client.

Plant Background

This plant produces stainless steel pipes of various diameters

and lengths and custom-made pipe fittings. It operates over

6,240 hr/yr to produce nearly 30 million pounds of pipe annually.

Manufacturing Process

Raw materials used by the plant include coil and sheet metal

stock, solvent-based marking ink, and protective plastic end

caps. The two major operations in this plant, pipe and fitting

formation and acid pickling, are described in this section.

Pipe and Fitting Formation

Stainless steel coil and sheet stock is unloaded and stored

outdoors under protective cover. As it is needed, the coil stock

is moved indoors by forklift to one of six automatic tube mills

where the sides of unrolled metal strips are curled up to form a

continuous, cylindrical pipe. The seam of the resulting pipe is

fused in an electric in-line welding operation. An abrasive saw

is used to cut the continuously-formed pipe to specified lengths;

sections of poorly welded pipe are cut away.

Stainless steel sheet stock is used to form custom products

such as T’s, elbows, and reducers. The sheets are cut with a

band saw or plasma torch into smaller pieces and customformed into final product shapes using various forming and

bending equipment.

All pipes and fittings are hardened in electric induction or gas

annealing furnaces. After annealing, the pipes are water sprayquenched or quenched in a water-filled tank outdoors, depending on their size.

The roughened ends of the pipe are manually deburred with an

air grinder. Then the pipes are straightened as necessary and

transported to the acid pickling process.

Acid Pickling

All pipes and fittings are transported to the pickling process in

which an overhead crane is used to lower them into an acidic

pickle liquor solution which chemically cleans and etches the

black oxide surface layer resulting in a clean, rust resistant

pipe.

Each pipe is rinsed with water in one of two rinse tanks and is

then mounted on a wash rack and manually sprayed with water

in a second rinsing operation. After the pipes dry, they are

labeled with a solvent-based ink spray jet and protective plastic

caps are hammered onto the ends. The finished products are

stored outdoors until they are shipped to customers.

An abbreviated process flow diagram for pipe production is

shown in Figure 1.

Steel Coil and Sheet Stock

Outdoor

Storage Tube Mills Welding

Quenching Annealing Cutting

Deburring Straightening Acid

Packaging Air Drying Rinsing

Finished Pipe Shipped to Customers

Pickling

Figure 1. Abbreviated process flow diagram for straight pipe manufacture.
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Existing Waste Management Practices

This plant already has implemented the following techniques to

manage and minimize its wastes:

• The polymer previously used by this plant as a flocculent in

the onsite wastewater treatment system has been replaced

by magnesium hydroxide in order to reduce the volume of

sludge generated and shipped offsite.

• An acid regeneration system has been installed to regenerate spent pickle liquor for reuse onsite.

Pollution Prevention Opportunities

The type of waste currently generated by the plant, the source

of the waste, the waste management method, the quantity of

the waste, and the annual waste management cost for each

waste stream identified are given in Table 1.

Table 2 shows the opportunities for pollution prevention that

the WMAC team recommended for the plant. The opportunity,

the type of waste, the possible waste reduction and associated

savings, and the implementation cost along with the simple

payback time are given in the table. The quantities of waste

currently generated by the plant and possible waste reduction

depend on the production level of the plant. All values should

be considered in that context.

It should be noted that the financial savings of the opportunities

result from the need for less raw material and from reduced

present and future costs associated with waste management.

Other savings not quantifiable by this study include a wide

variety of possible future costs related to changing emissions

standards, liability, and employee health. It also should be

noted that the savings given for each pollution prevention

opportunity reflect the savings achievable when implementing

each opportunity independently and do not reflect duplication

of savings that would result when the opportunities are implemented in a package.

Additional Recommendations

In addition to the opportunities recommended and analyzed by

the WMAC team, several additional measures were considered. These measures were not analyzed completely because

of insufficient data, implementation difficulty, or a projected

lengthy payback. Since one or more of these approaches to

pollution prevention may, however, increase in attractiveness

with changing conditions in the plant, they were brought to the

plant’s attention for future consideration.

• Recycle waste packaging material that is currently shipped to

the municipal landfill.

• Periodically renew the filter press cloths that have lost the

maximum potential to pass clean water from the wastewater

treatment sludge.

• Modify material handling procedures in order to remove

metal shavings that have fallen inside the pipes during the

mill process prior to the acid pickling process. Implementation of this measure will lead to reduced generation of

hazardous sludge.

• Remove pipe surface oxide flakes in a high-pressure spray

wash or with mild mechanical abrasion to reduce the quantity

of flakes carried over into the pickling tanks.

This research brief summarizes a part of the work done under

Cooperative Agreement No. CR-819557 by the University City

Science Center under the sponsorship of the U.S. Environmental Protection Agency. The EPA Project Officer was Emma

Lou George.

Table 1. Summary of Current Waste Generation

Annual Quantity Annual Waste

Waste Generated Source of Waste Waste Management Method Generated (lb/yr) Management Cost

Packaging and protective barrier waste Receipt and storage of raw materials Shipped to municipal landfill 7,500 $01

Leaked and spent lubricating oil Machining Shipped to fuels blending program 8,540 5,980

Spent abrasive saw blades Cutting of pipe Shipped to municipal landfill 5,200 01

Stainless steel scrap Machining and cutting of pipe Sold to scrap recycler 700,000 -164,300

(net revenue received)

Oxidized metal flakes and metal dust Annealing, deburring, and cutting Shipped to special landfill 30,000 15,810

Quench water Quenching of pipes following annealing Sewered to POTW 49,800 40

Damaged plastic end caps Packaging of finished product Shipped to municipal landfill 130 01

Pickling rinse water Acid pickling of product Treated in onsite WWTP; 84,598,000 89,100

sewered to POTW

Wastewater treatment sludge Onsite treatment of wastewater Shipped to hazardous waste landfill 1,560,000 265,370

Miscellaneous solid waste Various plant operations Shipped to municipal landfill 135,000 cu ft2 26,990

1 Included in annual waste management cost for miscellaneous solid waste.

2Includes specific quantities given for packaging and protective barrier waste, spend abrasive saw blades, and damaged plastic

 end caps. The majority of this waste stream is cardboard waste.
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Table 2. Summary of Recommended Pollution Prevention Opportunities

Annual Waste Reduction

Net Annual Implementation Simple

Pollution Prevention Opportunity Waste Reduced Quantity (lb/yr) Percent Savings Cost Payback (yr)

Install a propane-fired sludge drying oven to reduce Wastewater 928,200 60 $141,150 $66,200 0.5

the volume and weight of the sludge that is generat- treatment sludge

ed in the onsite wastewater treatment system and

shipped offsite.

Utilize a trash compactor to reduce the volume of Miscellaneous 01 0 12,810 15,000 1.2

municipal trash shipped offsite, thereby reducing solid waste

disposal costs.

Remove the poor quality length of each coil of raw n/a —- —- 9,300 0 0

material prior to forming in the mills. Current practice is for the entire length of raw material to undergo the normal forming and welding operations, regardless of the quality. The current procedure leads

to unnecessary expenditures of welding gases,

worker labor, and energy.

Automate the addition of caustic to the wastewater n/a —- —- 12,620 12,600 1.0

treated in the onsite wastewater treatment plant in

order to reduce caustic purchases and reduce

labor costs.

1 A significant volume reduction would occur.

United States

Environmental Protection Agency

National Risk Management Research Laboratory (G-72)

Cincinnati, OH 45268

Official Business

Penalty for Private Use

$300

EPA/600/S-95/017

BULK RATE

POSTAGE & FEES PAID

EPA

PERMIT No. G-35