Material

  • A. General Properties Of Polymers

    Property Specific Gravity Water Absorption (%) Hardness Rockwell Yield (pst) Tensile Strength Notched (ft. It/in) Impact Strength (ft. Lb/in) Elongation At Break Temp (0c) HDT (0c) Injection Moulding Temp.(0c) Max Working Temp (0c)
    NORMAL GRADE PP 0.90 -0.91 0.01 -0.03 50 4400 1.5-2.5 200 90 200-300 80-85
    ISOTACTIC PP 0.90 0.01 70 4800 2.2-2.7 200 142 200-300 120
    PVDF 1.77 1.78 0.03 76-80 7000 2.0-4.0 50-250 168 200-300 -40 to +140
    ETFE 1.70 15 75 0.007 6700 2.0 300 176 310-330 -100 to +160
    FEP 2.15 0.004 60 3400 2.9 325 260 350-370 205
    PFA 2.15 < 0.03 72 3600 1.2 300 305 350-370 260

  • B. Advantages of Isotactic PP V/s Normal Grade PP

    • ISOTACTIC PP is a fractional MFI homopolymer therefore it has sufficiently better toughness than any other homopolymer.

    • Due to the presence of atmospheric oxygen, degradation and oxidation of NORMAL GRADE PP is inevitable even when there direct sunlight, while ISOTATIC PP is immune to such degradation and oxidation.

    • Chemical resistance of ISOTACTIC PP is more than that of NORMAL GRADE PP even at an elevated temperature.

    • ISOTACTIC PP has excellent heat resistance upto 120°C as against 85-90°C of NORMAL GRADE PP, w.r.t water.

    • This grade is proven in pickling lines (CRM) as well as ARP in steel Industries for handling HCL containing ferrous and ferric chlori an elevated temp. upto 110°C.

    • This grade is also proven in Caustic Chloro Plant for application in brine for Anolyte and Catholyte service upto 100°C.

    • This grade is also proven in application of HCL with solvent traces such as benzene, toluene etc. at an elevated temperature upto 110°C.

  • C. Unique Properties of Lining Materials

    PTFE (POLYTETRAFLUOROETHYLENE)

    PTFE has excellent properties such as chemical inertness, heat resistance (both high and low), electrical insulation properties, low coefficient of friction (Static 0.08 and Dynamic 0.01), and nonstick property over a wide temperature range up to 260°C. It has a density in the range of 2.1 to 2.3 g/cm³ and melt viscosity in the range of 25 MPa.s (CP). Molecular weight of PTFE cannot be measured by standard methods. Instead, an indirect approach is used to judge molecular weight. Standard Specific Gravity (SSG) is the specific gravity of a chip prepared according to a standardized procedure. The underlying principle is that lower molecular weight PTFE crystallizes more extensively, thus yielding higher SSG values.

    TFM™ PTFE

    The new generation of chemically modified PTFE enhances the performance of classic PTFE by providing outstanding low deformation under load, compression stress relaxation (recovery), reduced permeation, fewer voids, increased surface smoothness and good welding characteristics

    PFA (PER FLURO ALKOXY) (A POLYMER OF TETRAFLUOROETHYLENE AND PERFLUOROVINYLETHER)

    Fluorinated ethylene-propylene copolymers are fully fluorinated and melt-processible. They have excellent chemical resistance and thermal stability. Specific gravity of FEP resins is in the range of 2.13 to 2.15. FEP has an upper continuous use temperature of 200°C.

    ETFE (ETHYLENE TETRA FLUORO ETHYLENE) (A POLYMER OF TETRAFLUOROETHYLENE AND ETHYLENE)

    ETFE crystallizes into unit cells believed to be orthorhombic or monoclinic. The molecular conformation of ETFE is an extended zigzag. This polymer is dissolved in some boiling esters at above 230°C, thus allowing determination of molecular weight (weight-average) by light scattering. ETFE has several transitions, alpha relaxation at 110°C (shifts to 135°C at higher crystallinity), beta at 25°C and gamma relaxation at 120°C. ETFE has good mechanical properties including tensile and cut-through resistance and lower creep than perfluoropolymers. ETFE is more resistant to radiation than perfluoropolymers (modestly affected up to 20 Mrad) and can be crosslinked by radiation such as electron beam. Crosslinking is used to strengthen cut- through resistance of ETFE wire insulation.

    ECTFE

    Halar® ECTFE is a partially fluorinated semi-crystalline polymer offering a unique combination of properties for highly demanding industries.

    • Outstanding chemical, permeation and fire resistance

    • Low permeability

    • Excellent weatherability

    • Excellent release properties

    • Good abrasion resistance

    It is widely used in anti-corrosion applications as a lining or in self-supporting constructions (piping). Its excellent fire resistance properties and chemical resistance make Halar® ECTFE a product of first choice in wire and cable applications, in communication cable or speciality cable.

    PPH (POLYPROPYLENE HOMOPOLYMER)

    Polypropylene is available in two basic types as either homo polymer or copolymer material. Although similar in many respects each type exhibits distinct differences in both appearance and performance. Polypropylene Homopolymer (PPH) is the most widely utilized. PPH offers a high strength to weight ratio and is stiffer and stronger than copolymer, this combined with good chemical resistance and weldability allows this material to be used in many corrosion resistant structures.

    PFA (CONDUCTIVE / ANTI-STATIC)

    3M Dyneon™ Fluoroplastic PFA 8502ESDZ is an electrostatic dissipative fluorothermoplastic compound consisting of a fully fluorinated PFA base polymer and an electroconductive carbon black. The product has specifically been developed for transfer moulding.

    • Electrostatic dissipative

    • Processing : Transfer moulding

    • Wide service temperature range upto 2400C

  • D. Special Features of Unp Lined Valves

    Features Options Available
    CASTINGS All castings used are investment castings and only for large size UNP uses sand castings. Investment castings are used to obtain homogeneous and intact lining quality with uniform lining thickness which provides UNP valve a reliable lining quality and long lasting performance. ASTM A216 GR. WCB
    ASTM A351 GR. CF8
    ASTM A351 GR. CF8M
    ASTM A351 GR. CF3M
    ASTM A352 GR. LCB OR LCC
    ASTM A890 GR. 4A (CD3MN)
    ASTM A494 HASTELLOY C276 / C 22
    TRIM INSERTS UNP through its stringent design considerations has taken both the aspects of corrosion resistance and mechanical strength. Considering high torques in case of butterfly and plug valves UNP decided to use ASTM A890 GR. 4A(CD3MN) duplex material to obtain high "MAST" (Maximum Allowable Shear Torque) values ensuring intactness of plug and disc shafts even at higher operational torques. For other valves UNP uses trim inserts at higher grade of metal as ASTM A351 GR. CF8. ASTM A351 GR. CF8
    ASTM A351 GR. CF8M
    ASTM A351 GR. CF3M
    ASTM A890 GR. 4A (CD3MN)
    ASTM A494 HASTELLOY C276 / C22
    BODY BOLTS UNP uses allen bolts or stud & nut combination and high tensile body bolts are used considering its mechanical as well as corrosion aspects. SS 304
    SS 316
    SS 316L
    ALLOY 20
    ASTM A193 GR. B7 &
    A194 GR. 2H
    ASTM A494 HASTELLOY C276/ C22
    MONEL
    LINING MATERIALS UNP uses 100% virgin lining materials and is buying directly from the sources such as dyneon, chemours, solvay, llyondell basell etc. ensuring that the best and uniform quality of lining is done for UNP valves ensuring high reliability in terms of life and performance. PFA
    FEP
    ETFE PVDF PPH
    ECTFE
    ANTI-STATIC PFA
    PAINTING OF VALVES UNP has best painting technique and is using two part epoxy paint with proper paint procedure Is of coat of epoxy primer and 2nd & 3rd coat of epoxy paint with minimum DFT of 150 microns. Painting is most important in the UNP valve as it provides protection against most corrosive environment making the valve to survive against most corrosive environment and provides metal a very long life. TWO PART EPOXY POLYEURATHENE OR ANY OTHER PAINT WITH DIFFERENT RAL CODES.