Rupture Disc FAQ

<body topmargin=0 leftmargin=0 marginheight=0 marginwidth=0> <table cellpadding=0 cellspacing=0 border=0><tr> <td valign="top" colspan=2 height=90 BGCOLOR="#336699" TEXT="#080000" bgproperties="fixed" background="66b00c10erlcin.jpg"> <div> <FONT SIZE="2" COLOR="#FF6600" FACE="Arial" ><A HREF="index.htm" TARGET="_top" TITLE="PRD Technologies Inc."><U><B>HOME </B></U></A><B> </B></FONT><B>   </B><A HREF="id56.htm" TARGET="_top" TITLE="Rupture Disc FAQ"><U><B> </B></U></A><FONT SIZE="2" COLOR="#FF6600" FACE="Arial" ><A HREF="id56.htm" TARGET="_top" TITLE="Rupture Disc FAQ"><U><B> BACK </B></U></A></FONT><A HREF="id56.htm" TARGET="_top" TITLE="Rupture Disc FAQ"><U><B> </B></U></A><B>|  </B><FONT SIZE="7" COLOR="#FF6600" FACE="Arial" ><B> </B></FONT><FONT SIZE="7" COLOR="#FFFFCC" FACE="Arial" ><B>  </B></FONT><FONT SIZE="6" COLOR="#FFFFFF" FACE="Arial" ><B>PRD Technologies Inc.</B></FONT></div> <bR> <div> <B>Rupture Disc FAQ</B></div> </td> </tr><tr> <td valign="top" width=210 BGCOLOR="#FFFFFF" TEXT="#080000"> <div> Rupture Disc FAQ</div> <div> <B><IMG SRC="0ff5a740.jpg" border=0 width="90" height="116" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></div> <div> <B><IMG SRC="41a9b3e0.png" border=0 width="155" height="62" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></div> <div> <B>Answers</B></div> <bR> <div> <A HREF="id51.htm" TARGET="_top" TITLE="FAQ"><U><B>Return to main FAQ page</B></U></A></div> </td> <td valign="top" height=390 BGCOLOR="#FFFFFF" TEXT="#080000"> <div> <B>What is a rupture disc?</B></div> <div> The pressure-containing element of a rupture disc device, which consists of the rupture disc itself and a holder assembly. A rupture disc is designed to burst open and relieve an overpressure or vacuum condition at a predetermined differential pressure, and specific temperature.</div> <bR> <div> <B> <A NAME="faq2"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A></B><B>Which rupture disc design should I specify?</B></div> <div> No single type of rupture disc is the best fit for all the numerous applications of an industry. Continental Disc has a full line of rupture discs in both tension and reverse acting designs to meet the design criteria or requirements of most any application. Each type of rupture disc, however, has its own characteristics and capabilities. We can make available individual product bulletins outlining each rupture disc design's capabilities. You can contact our PRD offices for assistance in specifying a suitable rupture disc device.</div> <bR> <div> <B> <A NAME="faq3"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A></B><B>Which rupture disc devices are available to comply with ASME Code, Section VIII, Division? </B></div> <div> The complete line of CERTIFLOW™ rupture discs meets all of the new ASME Code requirements, including UD Code Symbol, and certified flow resistance (KR) and minimum net flow area (MNFA) values, certified by The National Board of Boiler and Pressure Vessel Inspectors.</div> <bR> <div> <B> <A NAME="faq4"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A></B><B>What's the difference between tension type and reverse acting rupture discs?</B></div> <div> Tension type rupture discs are oriented in a system with the process media pressure against the concave side of the rupture disc. As the process pressure increases beyond the allowable operating pressure, the tensile strength of the material is reached and rupture occurs.</div> <div> Reverse Acting rupture discs are oriented in a system with the process media pressure against the convex side of the disc, placing the rupture disc in compression. As the burst pressure rating of the disc is reached, the compression loading on the rupture disc causes it to reverse, snapping through the neutral position and causing it to open by a predetermined scoring pattern or knife blade penetration. </div> <bR> <div> <B> <A NAME="faq5"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A></B><B>The rupture disc keeps breaking early, what's wrong?</B></div> <div> Several factors can limit the usable life span of a rupture disc, or derate the rupture disc, causing it to burst at a lower pressure. Some of these include: pressurizing the system above the operating-to-burst-pressure ratio; handling or installation damage; damage from corrosive media; "shock" damage from system pulsations; and improper installation, which may include installing the rupture disc upside down, misaligned, overtorqued, undertorqued, failing to install all rupture disc elements, and installing the wrong rupture disc in a particular installation. Some of our rupture disc designs minimize or eliminate some of these problems. If there is a problem with your overpressure safety system, call us our CDC Tech Team is skilled in investigating problems and finding solutions.</div> <bR> <div> <B> <A NAME="faq6"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A></B><B>How do I know if the rupture disc is installed correctly?</B></div> <div> Use the Installation Instruction sheet supplied with your rupture discs. Each Installation Instruction was written specifically for a particular rupture disc design, and describes the installation procedures in detail to minimize the chance of improper installation. </div> <div> Other Continental Disc Corporation features that minimize error include C.D.C.'s innovative Three-Dimensional Flow Direction Tag which is permanently attached to most rupture disc designs, and provides instant visual verification that the rupture disc has been correctly oriented into the system. The 3-D tag extends beyond the holder to insure clear visibility for easier installation and inspection after the rupture disc has been installed. A customer-supplied identification number, pinstamped on the tag, allows for easy verification of your inventory using your system numbers. </div> <div> Alignment pins are installed in some rupture disc holders. Designed to mate with holes in the rupture disc, these pins provide positive alignment and assure the rupture disc is correctly oriented in the holder. </div> <div> A J-Hook, welded to the rupture disc holder inlet, provides easy alignment and proper orientation relative to the flow direction. Plus, stainless steel tags, attached to the holder inlet and outlet, specify the proper flow direction.</div> <div> Encapsulating rings are available for most designs. These provide a solid place for installers to hold rupture discs during installation, which is especially important for thinner rupture discs (usually with lower pressure ratings). </div> <div> The best method to prevent installation problems is education in proper installation techniques. Contact us to learn more about proper techniques, or about attending a technical seminar.</div> <bR> <div> <B> <A NAME="faq7"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A></B><B>What can I do to make sure the rupture disc operates as intended?</B></div> <div> Proper rupture disc operation is mostly dependent on two factors: specifying the design correctly, and proper installation. Contact our PRD offices if you are concerned about ensuring proper operation in your overpressure relief systems.</div> <bR> <div> <B> <A NAME="faq9"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A></B><B>We re-evaluated our relief system, and it no longer meets ASME Code relieving requirements. What can I do?</B></div> <div> Our rupture disc designs each have different certified flow resistance values. A newer rupture disc design or a different configuration may allow for greater relief capacity. In some cases, simply using the certified value (rather than an industry standard estimate) can show that an existing system meets new requirements. Check out our <U>CERTIFLOW™ literature</U> to see if using our certified flow resistance values can help you meet your requirements.</div> <bR> <div> <B> <A NAME="faq10"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A></B><B>Why aren't rupture discs kept in stock at PRD or C.D.C.?</B></div> <div> The variety of rupture disc configurations (size, pressure, temperature, material, linings, holder design, options) prevent PRD or C.D.C. from maintaining stock on all rupture discs. Each lot is made to the customer's particular specifications. This is one reason why rupture disc prices may change from one order to the next; issues like lot quantity and material cost have greater importance when the product is built to order.</div> <bR> <div> <B> <A NAME="faq11"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A></B><B>How do I identify my rupture discs / How do I reorder replacement rupture discs?</B></div> <div> Every rupture disc lot made by Continental Disc Corporation is traceable; the Manufacturing Number (pinstamped on the 3-D Tag or on the device) tells C.D.C. everything about that rupture disc, right down to the particular roll of metal it was made from. Supplying C.D.C. with the Manufacturing Number insures that your new order will conform to the specifications of the previous one. Care should be taken, however, that your process environment has not changed since the last order. For example, if the process temperature was increased 100 degrees Fahrenheit since the last order, the rupture disc materials you are reordering may be inappropriate and should be ordered to correct requirements. C.D.C. will stamp any customer-supplied tag number on the 3-D tag, but the C.D.C. Manufacturing Number (also on the tag) is what we use to trace a lot of rupture discs.</div> <bR> <div> <B> <A NAME="faq12"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A></B><B>What is the difference between the manufacturing range and the burst tolerance?</B></div> <div> According to the ASME Code, Section VIII, Division 1: </div> <div> The <I>Manufacturing Design Range</I> is a range of pressure within which the marked burst pressure must fall to be acceptable for a particular requirement as agreed upon between the rupture disc manufacturer and the user or his agent. </div> <div> Simply put, the Manufacturing Range is the range of pressure in which a rupture disc's marked rating must fall, in order to be accepted by the customer. </div> <div> The Burst Tolerance is the acceptable range in which a rupture disc might be expected to burst. ASME code specifies a Burst Tolerance of +/- 5% for burst pressures 40 psig (2,8 barg) and above, and +/- 2 psig (0,14 barg) for burst pressures below 40 psig.</div> <div> In summary: the Manufacturing Range applies <I><B>during</B></I> the manufacturing process; Burst Tolerance applies to the marked burst pressure <I><B>after</B></I> the manufacturing process is done.</div> <div> Some of our rupture disc designs are available with a ZERO manufacturing range: the burst pressure you specify will be exactly the burst pressure marked on the tag. See the individual product bulletins for details concerning Manufacturing Range, Burst Tolerance, and Zero Manufacturing Range rupture discs.</div> <div> <B> <A NAME="faq13"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A></B><B>Is my rupture disc interchangeable with other manufacturers?</B></div> <div> Many rupture discs use special holder designs, or patented features which make interchangeability with other manufacturers' holders impossible. Additionally, for installations which require adherence to ASME Code, the certified flow resistance is valid only for that combination of rupture disc and holder which was tested by the manufacturer and certified by The National Board of Boiler and Pressure Vessel Inspectors. Contact our PRD offices for interchangeability in non-ASME Code installation.</div> <bR> <div> <B> <A NAME="faq14"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A></B><B>I don't see what I need in the Continental Disc Corporation Catalog.</B></div> <div> Continental Disc Corporation has built a 35-year reputation for solving the toughest pressure relief problems. Solving pressure relief problems for you is the special role played by C.D.C.'s Product Development Group and the Special Products Group. This pool of product development expertise has been retrofitting C.D.C. designs into clients' systems for more than 35 years. C.D.C. is ready to solve your special pressure relief problems. Contact our PRD offices to find your solution.</div> <bR> </td> </tr></table></body>