6 Our largest business segment is FPD, through which we design, manufacture, pre-test, distribute and service specialty and highly-engineered custom and pre-configured pumps and pump systems, mechanical seals, auxiliary systems, replacement parts and upgrades and related aftermarket services (collectively referred to as "aftermarket"). FPD products and services are primarily used by companies that operate in the oil and gas, petrochemical, chemical, power generation, water management and general industries. We market our pump and mechanical seal products through our global sales force and our regional QRCs and service and repair centers or through independent distributors and sales representatives. A portion of our mechanical seal products are sold directly to other original equipment manufacturers for incorporation into their rotating equipment requiring mechanical seals. FLOWSERVE PUMP DIVISION BUSINESS SEGMENTS Exports We report a two operating segment structure, consisting of our Flowserve Pumps Division and our Flow Control Division. In addition to the business segment information presented below, Note 20 to our consolidated financial statements in Item 8 of this Annual Report contains additional financial information about our business segments and geographic areas in which we have conducted business in 2020, 2019 and 2018. Our export sales from the U.S. to foreign unaffiliated customers were $264.6 million in 2020, $300.9 million in 2019 and $234.3 million in 2018. Licenses are required from U.S. and other government agencies to export certain products. In particular, products with nuclear power generation and/or military applications are restricted, as are certain other pump, valve and seal products. We have established reserves that we currently believe to be adequate to cover our currently identified on-site and off-site environmental liabilities. We use hazardous substances and generate hazardous wastes in many of our manufacturing and foundry operations. Most of our current and former properties are or have been used for industrial purposes and some may require clean-up of historical contamination. During the due diligence phase of our acquisitions, we conduct environmental site assessments to identify potential environmental liabilities and required clean-up measures. We are currently conducting follow-up investigation and/or remediation activities at those locations where we have known environmental concerns. We have cleaned up a majority of the sites with known historical contamination and are addressing the remaining identified issues. Over the years, we have been involved as one of many potentially responsible parties ("PRP") at former public waste disposal sites that are or were subject to investigation and remediation. We are currently involved as a PRP at four  Superfund sites. The sites are in various stages of evaluation by government authorities. Our total projected "fair share" cost allocation at these four  sites is expected to be immaterial. See "Item 3. Legal Proceedings" included in this Annual Report for more information. We are subject to environmental laws and regulations in all jurisdictions in which we have operating facilities. These requirements primarily relate to the generation and disposal of waste, air emissions and waste water discharges. We periodically make capital expenditures to enhance our compliance with environmental requirements, as well as to abate and control pollution. At present, we have no plans for any material capital expenditures for environmental control equipment at any of our facilities. However, we have incurred and continue to incur operating costs relating to ongoing environmental compliance matters. Based on existing and proposed environmental requirements and our anticipated production schedule, we believe that future environmental compliance expenditures will not have a material adverse effect on our financial condition, results of operations or cash flows. "black belts" or "green belts" and deploying them to CIP led projects throughout the Company. As a result, we have developed and implemented processes to shorten engineering and manufacturing cycle times, improve on-time delivery and service response time, lower inventory levels and otherwise reduce costs. To date, ov er 800 of our employees are CIP certified. Environmental Regulations and Proceedings