embodiments of the present invention will now be described with respect to the figures , with the understanding that the figures and description are directed to the preferred embodiments of the present invention . for example , the present invention will be described in detail with respect to a check valve . individuals skilled in the art will recognize that features of the present invention have application in many devices which hold or transport fluids under pressure . turning now to fig1 , a device , for holding fluids at high pressures , generally designated by the numeral 11 , is depicted . the device 11 , for receiving and discharging fluids , is in the nature of a check valve . device 11 comprises a first housing 13 , an end cap 15 , at least one seal coating 17 and compression means 19 . turning now to fig2 , the first housing 13 has at least one side wall 25 . side wall 25 has an interior surface 27 a and an exterior surface 27 b . the interior surface 27 a defines at least one chamber 29 , preferably , cylindrical in shape . interior surface 27 a has at least one end cap abutment surface 31 for receiving the end cap 15 . preferably , the end cap abutment surface 31 is recessed into chamber 29 to facilitate positioning of the end cap 15 . as depicted , interior surface 27 has a recess section 33 forming the recess for receiving end cap 15 . the housing 13 has an end wall 35 having an interior surface 37 a and an exterior surface 37 b . the end wall 35 closes the chamber 29 defined by the interior surface 27 a of the side wall 25 . end cap 15 is cylindrical in shape to cooperate with the recess section 33 of the interior surface 27 a of the first housing 13 . end cap 15 has at least one first housing abutment surface 39 . turning now to fig3 and 4 , alternative embodiments of end cap 15 are disclosed . the end cap 15 of fig2 is illustrated in greater detail in fig3 . end cap abutment surface 39 is a ridge 39 a to localize compression forces on said seal coating 17 . the ridge 39 a is a protrusion jutting upward from a planar surface 39 b . the ridge 39 a is capable of contact with an opposing abutment surface such as end cap abutment surface 31 of the first housing 13 . the ridge 39 a localizes or focuses compression forces in a small area . turning now to fig4 , a further embodiment of the end cap 15 is illustrated , generally designated by the numeral 15 ′. end cap 15 ′ is cylindrical in shape to cooperate with the recess section 33 of the interior surface 27 a of the first housing 13 . end cap 15 ′ has at least one first housing abutment surface 39 ′. in this embodiment , the first housing abutment surface 39 ′ is planar , without any protruding surface features . the abutment surface 39 ′ is capable of contact with an opposing abutment surface such as end cap abutment surface 31 of first housing 13 . the first housing abutment surface 31 receives the end cap abutment surface 39 and 39 ″ positioning the end cap 15 and / or 15 ′ on the first housing 13 for enclosing the chamber 29 . the end cap 15 and / or 15 ′ and first housing are typically made of stainless steel ; however , other materials can readily be substituted . in the case where , the first housing 13 and end cap 15 and / or 15 ′ are parts of a check valve , the first housing 13 is approximately 0 . 25 to 0 . 75 mm in length and diameter . the end cap 15 and or 15 ′ are approximately 0 . 1 to 0 . 70 in diameter and 0 . 1 to 0 . 2 mm in thickness . at least one of the first housing abutment surface 39 and / or 39 ′ and the end cap abutment surface 31 has first seal coating 17 . the first seal coating 17 comprises a deformable plastic adhering to first housing abutment surface 31 and / or 31 ′ or the end cap abutment surface 39 . seal coating 17 is selected from one or more of the polymeric coatings consisting of polytrifluoroethylene ( ptfe ), polyetheretherketone ( peek ), polychlorotrifluoroethylene ( pctfe ), perfluoroalkoxy ( pfa ) and fluorinatedethylenepropylene ( fep ). the polymeric coating is applied to the entire end cap 15 and / or 15 ′ or the first housing abutment surface 31 and / or 31 ′ to a thickness of 0 . 0005 - 0 . 0025 inches , and most preferably , approximately 0 . 0010 to 0 . 0015 inches . methods of placing a polymeric coating on a metal substrate are well known in the art . the device 11 further comprises fluid path means for receiving and removing fluid from the chamber . referring now to fig3 and 4 , the end cap 15 and 15 ′ have an end cap opening 45 . and , returning now to fig1 , the first housing has a first housing opening or more preferably a pair of first housing openings 47 a and 47 b for introducing fluids into the chamber 29 . preferably , the pair of openings are set off axis for check valve applications in end wall 35 . the end cap opening 45 and first housing openings 47 a and 47 b may comprise any ports , conduits and pipes that provide fluid . thus , embodiments of the present invention can be placed inline , with fluid path means comprising conduits and pipes or incorporated within the housing of a larger structure , for example , without limitation , as depicted in fig1 , a pump head or pump housing 49 . the device 11 comprises compression means 19 to compress the end cap 15 and / or 15 ′, with the end cap abutment surface 31 and / or 31 ′ received on said first housing abutment surface 39 , towards said first housing 13 . the compression deforms the first seal coating 17 and seals the chamber . as illustrated in fig1 , the compression means 19 comprises pump housing 49 , compression housing 51 and screw fitting 53 . it will be recognized by those skilled in the art that pump housing 49 may be substituted with a further fitting that cooperates with compression housing 51 and screw fitting 53 , to allow the device 11 to be placed in a fluid line . embodiments of the present invention are ideally suited for fittings and valves . where the device is in the form of a valve , referring to fig2 , the chamber 29 contains a valve assembly 61 . the valve assembly 61 may comprise rotary - type valves ( not shown ), gated valves ( not shown ) or check valves , to described in further detail . in the case where the device is in the form of a check valve , the first housing 13 has at least one end wall 65 opposite the end cap 15 or 15 ′. the fluid path means comprises at least one opening 45 in said end cap 15 or 15 ′ and at least one opening , and preferably two , 47 a and 47 b , in said end wall 65 . chamber 29 holds a valve assembly 61 comprising a ball seat 71 and a ball 73 . preferably , the interior wall 27 a has a first ball seat abutment surface 77 . and , the end cap 15 and / or 15 ′ has a ball seat abutment surface 79 . the ball seat 71 comprises a cylinder section 81 having a first rim 83 , a second rim 85 and a fluid passage 87 . the first rim 83 has a ball receiving surface 89 for engaging the ball 73 and closing the fluid passage 87 . second rim 85 has a rim abutment surface 91 and end cap 15 and / or 15 ′ has a ball seat abutment surface 79 . preferably , at least one of the rim abutment surface 91 and ball seat abutment surface 79 has a ball seat seal coating 95 . the ball seat seal coating 95 engages the abutment surface opposite to that it is placed and seals the ball seat and the housing 13 and / or end cap 15 and / or 15 ′. the ball seat coating 95 may comprise a portion of the seal coating 17 on the end cap 15 and / or 15 ′. preferably , the ball seat coating is made and formed as described above with respect to the seal coating 17 . the exterior surface 37 b of end wall 35 has an end wall abutment surface 99 encircling the one or more end wall openings 47 a and 47 b . preferably , the end wall abutment surface 99 has an end wall seal coating 101 . the end wall seal coating 101 is a deformable plastic made and formed as described above with respect to the seal coating 17 . the end wall seal coating 101 sealably engages an adjoining wall to which it is compressed . devices of this type are well suited to be mounted in a further major housing structure having the adjoining wall . for example , turning now to fig1 , the end wall seal coating 101 engages the adjoining wall 105 of a pump head housing 49 . in this embodiment , preferably , the adjoining wall 105 has an opening 103 for the passage of fluid into the end wall opening ( not shown ). in this embodiment , the compression means 19 comprises such adjoining wall 105 and a cylindrical wall 107 for receiving the end wall abutment surface 99 and compressing the end wall seal coating 101 in sealing engagement . the compression means 19 comprises a compression assembly comprising a compression housing 51 and compression sleeve 53 . the compression housing 51 has a compression chamber 113 for receiving the first housing 13 and the end cap 15 and / or 15 ′. the compression sleeve 53 engages the compression housing 51 for placing said end cap 15 and / or 15 ′, and first housing 13 under compression . preferably , the compression sleeve 53 and compression nut ( not shown ) or the pump head 49 or other apparatus to which it is placed has cooperating threads 115 as depicted in fig1 . the cooperating threads 115 engage upon relative rotation of the compression sleeve and pump housing 49 or compression nut ( not shown ). turning now to fig2 , the compression housing 51 has an second end cap abutment surface 117 . at least one of the end cap 15 and / or 15 ′ has a compression assembly seal coating 121 . the compression assembly seal coating 121 is a deformable plastic made and formed as described above with respect to the seal coating 17 . the compression assembly seal coating 121 sealably engages an adjoining wall to which it is compressed . in operation , a method of using the present invention to joining fluid passages comprises the steps of providing a device 11 having a first housing 13 , an end cap 15 and or 15 ′, a seal coating 17 and compression means 19 . the device has a fluid path means for receiving and removing fluid from the chamber 29 . the method further comprises the step of placing the receiving conduit and discharge conduits in communication with the fluid passages and compressing the seal coating 17 to seal the chamber 29 . the devices and methods of the present invention are ideally suited for high pressure applications . the devices made in accordance of the present invention do not have seals that exhibit material creep , cold flow and relaxation . that is , as the fluid pressure fluctuates , the seal coating do not move . the seal coatings are adhered to or fixed to one of the abutment surfaces . as such the seal coasting can not move or slip from an original position . thus , embodiments of the present invention provide devices which do not have gasket failure . these and other advantages and features will be apparent to those skilled in the art to which this invention relates and therefore the present invention should not be limited to the precise details disclosed herein but should encompass the subject matter of the claims that follow .