{"product_id":"cpi-1-1-4-fpt-raised-spinweld-fitting-1-3-4-hole-size-54ll-500151","title":"CPI - 1-1\/4\" FPT Threaded Raised Spinweld Fitting - 1-3\/4\" Hole Size - Part # 54LL (500151)","description":"\u003cdiv style=\"background:#f3f4f6;border-left:4px solid #1d9bf0;padding:16px;margin-bottom:12px;\"\u003e\u003cstrong style=\"color:#1d9bf0;\"\u003e✓ ElkhartRVParts.com - The Only Authorized Place for CPI (Custom Plastics)\u003c\/strong\u003e\u003c\/div\u003e\n\u003cdiv style=\"background:#f3f4f6;border-left:4px solid #10b981;padding:16px;margin-bottom:24px;\"\u003e\u003cstrong style=\"color:#10b981;\"\u003e✓ 100% Verified Authentic OEM Grade Part\u003c\/strong\u003e\u003c\/div\u003e\n\n\u003cp\u003eThe \u003cstrong\u003eCPI 1-1\/4\" FPT Threaded Raised Spinweld Fitting (Part #54LL \/ 500151)\u003c\/strong\u003e is the go-to solution for creating a secure, leak-resistant threaded connection on RV fresh water and holding tanks. The raised profile gives you extra clearance for fittings and hose connections, making installation and maintenance significantly easier than flush-mount alternatives.\u003c\/p\u003e\n\n\u003ch2\u003eFeatures \u0026amp; Specifications\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eThread Size:\u003c\/strong\u003e 1-1\/4\" FPT (Female Pipe Thread)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRequired Hole Size:\u003c\/strong\u003e 1-3\/4\" diameter\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFitting Style:\u003c\/strong\u003e Raised Spinweld\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eConnection Type:\u003c\/strong\u003e Threaded (FPT)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eApplication:\u003c\/strong\u003e RV Fresh Water Tanks \u0026amp; Holding Tanks\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Durable Plastic\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer:\u003c\/strong\u003e Custom Plastics (CPI)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePart Numbers:\u003c\/strong\u003e 54LL \/ 500151\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSold:\u003c\/strong\u003e Individually (Each)\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eWhy Choose the CPI Part #54LL Raised Spinweld Fitting?\u003c\/h2\u003e\n\u003cp\u003eThe \u003cstrong\u003eraised spinweld design\u003c\/strong\u003e of the Part #54LL sets it apart from standard flush fittings. The elevated boss gives you more thread engagement depth and easier access for wrenches and hose connections — critical when working in tight RV tank compartments. The spinweld installation method creates a permanent, vibration-resistant bond directly to your polyethylene tank wall.\u003c\/p\u003e\n\u003cp\u003eWith a perfect \u003cstrong\u003e5.0-star rating from 7 verified buyers\u003c\/strong\u003e, the CPI 54LL is a proven performer trusted by RV owners and repair shops alike. It's the same OEM-grade fitting used by RV manufacturers during original production.\u003c\/p\u003e\n\n\u003ch2\u003eCompare CPI Spinweld \u0026amp; Raised Tank Fittings\u003c\/h2\u003e\n\u003cp\u003eNot sure which CPI fitting is right for your application? Use this table to compare thread size, hole size, and fitting style across the CPI lineup.\u003c\/p\u003e\n\u003cdiv style=\"overflow-x:auto;\"\u003e\n\u003ctable style=\"width:100%;border-collapse:collapse;font-size:14px;\"\u003e\n\u003cthead\u003e\n\u003ctr style=\"background:#dc2626;color:#fff;\"\u003e\n\u003cth style=\"padding:10px;border:1px solid #e5e7eb;text-align:left;\"\u003ePart #\u003c\/th\u003e\n\u003cth style=\"padding:10px;border:1px solid #e5e7eb;text-align:left;\"\u003eThread \/ Size\u003c\/th\u003e\n\u003cth style=\"padding:10px;border:1px solid #e5e7eb;text-align:left;\"\u003eHole Size\u003c\/th\u003e\n\u003cth style=\"padding:10px;border:1px solid #e5e7eb;text-align:left;\"\u003eFitting Style\u003c\/th\u003e\n\u003cth style=\"padding:10px;border:1px solid #e5e7eb;text-align:left;\"\u003eBest For\u003c\/th\u003e\n\u003cth style=\"padding:10px;border:1px solid #e5e7eb;text-align:left;\"\u003eView Details\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding:10px;border:1px solid #e5e7eb;\"\u003e\u003cstrong\u003e#55 (500108)\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:10px;border:1px solid #e5e7eb;\"\u003e1-1\/4\" FPT\u003c\/td\u003e\n\u003ctd style=\"padding:10px;border:1px solid #e5e7eb;\"\u003e1-1\/2\"\u003c\/td\u003e\n\u003ctd style=\"padding:10px;border:1px solid #e5e7eb;\"\u003eFlat Spinweld\u003c\/td\u003e\n\u003ctd style=\"padding:10px;border:1px solid #e5e7eb;\"\u003eLow-profile flush mount applications\u003c\/td\u003e\n\u003ctd style=\"padding:10px;border:1px solid #e5e7eb;\"\u003e\u003ca href=\"\/products\/rv-tank-fittings1-1-4-fitting-2-hole-size\" style=\"color:#dc2626;\"\u003eView #55\u003c\/a\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"border-left:3px solid #dc2626;background:#fef2f2;\"\u003e\n\u003ctd style=\"padding:10px;border:1px solid #e5e7eb;\"\u003e\n\u003cstrong\u003e#54LL (500151)\u003c\/strong\u003e (This Product)\u003c\/td\u003e\n\u003ctd style=\"padding:10px;border:1px solid #e5e7eb;\"\u003e1-1\/4\" FPT\u003c\/td\u003e\n\u003ctd style=\"padding:10px;border:1px solid #e5e7eb;\"\u003e1-3\/4\"\u003c\/td\u003e\n\u003ctd style=\"padding:10px;border:1px solid #e5e7eb;\"\u003eRaised Spinweld\u003c\/td\u003e\n\u003ctd style=\"padding:10px;border:1px solid #e5e7eb;\"\u003eRaised clearance, easier hose\/fitting access\u003c\/td\u003e\n\u003ctd style=\"padding:10px;border:1px solid #e5e7eb;\"\u003e\u003cstrong\u003eCurrent Page\u003c\/strong\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding:10px;border:1px solid #e5e7eb;\"\u003e\u003cstrong\u003e#61 (500121)\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:10px;border:1px solid #e5e7eb;\"\u003e1-1\/4\" Spigot\u003c\/td\u003e\n\u003ctd style=\"padding:10px;border:1px solid #e5e7eb;\"\u003e1-1\/2\"\u003c\/td\u003e\n\u003ctd style=\"padding:10px;border:1px solid #e5e7eb;\"\u003eSpigot Spinweld\u003c\/td\u003e\n\u003ctd style=\"padding:10px;border:1px solid #e5e7eb;\"\u003eSlip-fit pipe connections (no threads)\u003c\/td\u003e\n\u003ctd style=\"padding:10px;border:1px solid #e5e7eb;\"\u003e\u003ca href=\"\/products\/rv-tank-fittings1-1-4-spig-spin-fitting-1-1-2-hole-size\" style=\"color:#dc2626;\"\u003eView #61\u003c\/a\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding:10px;border:1px solid #e5e7eb;\"\u003e\u003cstrong\u003e#65M (500502)\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:10px;border:1px solid #e5e7eb;\"\u003e2\" Raised\u003c\/td\u003e\n\u003ctd style=\"padding:10px;border:1px solid #e5e7eb;\"\u003e2-1\/2\"\u003c\/td\u003e\n\u003ctd style=\"padding:10px;border:1px solid #e5e7eb;\"\u003eRaised Fitting\u003c\/td\u003e\n\u003ctd style=\"padding:10px;border:1px solid #e5e7eb;\"\u003eLarger diameter raised connections\u003c\/td\u003e\n\u003ctd style=\"padding:10px;border:1px solid #e5e7eb;\"\u003e\u003ca href=\"\/products\/rv-tank-fittings2-raised-fitting-2-1-2-hole-size\" style=\"color:#dc2626;\"\u003eView #65M\u003c\/a\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\u003cp style=\"font-size:13px;color:#6b7280;margin-top:8px;\"\u003e\u003cem\u003eTip: Choose a raised fitting when you need extra clearance for hose connections or when working in tight tank compartments. Use a flush fitting when tank wall space is limited.\u003c\/em\u003e\u003c\/p\u003e\n\n\u003ch2\u003eTechnical Specifications\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePart Number:\u003c\/strong\u003e 54LL \/ 500151\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThread Size:\u003c\/strong\u003e 1-1\/4\" FPT (Female Pipe Thread)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRequired Hole Size:\u003c\/strong\u003e 1-3\/4\" diameter\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFitting Style:\u003c\/strong\u003e Raised Spinweld\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Durable Plastic\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCompatible Tanks:\u003c\/strong\u003e RV Fresh Water Tanks, RV Holding Tanks (polyethylene)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInstallation Method:\u003c\/strong\u003e Spinweld (heat-spin bonded to tank wall)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer:\u003c\/strong\u003e Custom Plastics (CPI)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCondition:\u003c\/strong\u003e New\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUnit:\u003c\/strong\u003e Sold individually (Each)\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eWhat's Included\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eOne (1) CPI 1-1\/4\" FPT Threaded Raised Spinweld Fitting — Part #54LL (500151)\u003c\/li\u003e\n\u003cli\u003e30-day return policy\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eCompatible Models \u0026amp; Alternatives\u003c\/h2\u003e\n\u003cp\u003eLooking for a different size or style? Browse related CPI fittings: \u003ca href=\"\/products\/rv-tank-fittings1-1-4-fitting-2-hole-size\" style=\"color:#dc2626;\"\u003e1-1\/4\" FPT Flat Spinweld #55\u003c\/a\u003e, \u003ca href=\"\/products\/rv-tank-fittings1-1-4-spig-spin-fitting-1-1-2-hole-size\" style=\"color:#dc2626;\"\u003e1-1\/4\" Spigot Spinweld #61\u003c\/a\u003e, and \u003ca href=\"\/products\/rv-tank-fittings2-raised-fitting-2-1-2-hole-size\" style=\"color:#dc2626;\"\u003e2\" Raised Fitting #65M\u003c\/a\u003e. Browse our full \u003ca href=\"\/collections\/rv-tank-fittings\" style=\"color:#dc2626;\"\u003eRV Tank Fittings collection\u003c\/a\u003e for the complete CPI lineup.\u003c\/p\u003e\n\n\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\n\u003ch3\u003eWhat hole size do I need to install the Part #54LL spinweld fitting?\u003c\/h3\u003e\n\u003cp\u003eThe CPI Part #54LL requires a \u003cstrong\u003e1-3\/4\" diameter hole\u003c\/strong\u003e in your tank wall for proper installation.\u003c\/p\u003e\n\n\u003ch3\u003eWhat is the thread size on the 54LL fitting?\u003c\/h3\u003e\n\u003cp\u003eThe fitting has \u003cstrong\u003e1-1\/4\" FPT (Female Pipe Thread)\u003c\/strong\u003e, which accepts standard 1-1\/4\" MPT male pipe thread fittings and adapters.\u003c\/p\u003e\n\n\u003ch3\u003eWhat is the difference between a raised and flush spinweld fitting?\u003c\/h3\u003e\n\u003cp\u003eA \u003cstrong\u003eraised spinweld fitting\u003c\/strong\u003e like the #54LL has an elevated boss above the tank wall, providing extra clearance for hose connections and easier wrench access. A flush fitting sits flat against the tank surface, which is better when space is extremely limited.\u003c\/p\u003e\n\n\u003ch3\u003eIs this fitting compatible with both fresh water and holding tanks?\u003c\/h3\u003e\n\u003cp\u003eYes — the CPI Part #54LL is designed for use with both \u003cstrong\u003eRV fresh water tanks and holding tanks\u003c\/strong\u003e (grey and black water) made from polyethylene.\u003c\/p\u003e\n\n\u003ch3\u003eHow is a spinweld fitting installed?\u003c\/h3\u003e\n\u003cp\u003eSpinweld fittings are installed using a drill and spinweld tool that spins the fitting at high speed against the tank wall, generating friction heat that fuses the fitting permanently to the polyethylene tank. This creates a leak-resistant bond without adhesives or sealants.\u003c\/p\u003e\n\n\u003ch3\u003eWhere can I buy the CPI Part #54LL spinweld fitting?\u003c\/h3\u003e\n\u003cp\u003eElkhartRVParts.com is an authorized CPI dealer. Order directly here for guaranteed authentic OEM-grade parts with fast shipping.\u003c\/p\u003e\n\n\u003ch2\u003eWhy Buy from Elkhart RV Parts?\u003c\/h2\u003e\n\u003cp\u003eAs an authorized CPI (Custom Plastics) dealer, every fitting you purchase from us is 100% genuine OEM-grade. We stock authentic parts, ship fast, and back every order with our 30-day return policy. Our team specializes in RV plumbing — we're here to make sure you get the right part the first time.\u003c\/p\u003e\n\n\u003cdiv style=\"background:#f3f4f6;border-left:4px solid #dc2626;padding:16px;margin-top:24px;\"\u003e\n\u003cstrong style=\"color:#dc2626;\"\u003eReady to order?\u003c\/strong\u003e Add the CPI Part #54LL to your cart today for fast shipping. Have a question about fitment or compatibility? Use our \u003cstrong\u003eAI Live Chat\u003c\/strong\u003e for instant answers from our RV parts experts.\n\u003c\/div\u003e","brand":"CPI","offers":[{"title":"Default Title","offer_id":32789642838075,"sku":"54LL\/500151","price":4.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0346\/2397\/9579\/files\/cpi-1-1-4-fpt-raised-spinweld-fitting-1-3-4-hole-size-54ll-500151-shopify-1.jpg?v=1779179090","url":"https:\/\/elkhartrvparts.com\/products\/cpi-1-1-4-fpt-raised-spinweld-fitting-1-3-4-hole-size-54ll-500151","provider":"Elkhart RV Parts","version":"1.0","type":"link"}