diff --git a/src/sampling/sampledSurface/writers/nastran/nastranSurfaceWriter.C b/src/sampling/sampledSurface/writers/nastran/nastranSurfaceWriter.C
index adfe60f566..384192756d 100644
--- a/src/sampling/sampledSurface/writers/nastran/nastranSurfaceWriter.C
+++ b/src/sampling/sampledSurface/writers/nastran/nastranSurfaceWriter.C
@@ -25,9 +25,9 @@ License
 
 #include "nastranSurfaceWriter.H"
 #include "IOmanip.H"
-#include "Tuple2.H"
-#include "makeSurfaceWriterMethods.H"
+#include "Pair.H"
 #include "HashSet.H"
+#include "makeSurfaceWriterMethods.H"
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
@@ -65,7 +65,7 @@ namespace Foam
 
 // * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
 
-void Foam::nastranSurfaceWriter::formatOS(OFstream& os) const
+void Foam::nastranSurfaceWriter::formatOS(Ostream& os) const
 {
     os.setf(ios_base::scientific);
 
@@ -76,19 +76,23 @@ void Foam::nastranSurfaceWriter::formatOS(OFstream& os) const
     label offset = 7;
     switch (writeFormat_)
     {
-        case (wfShort):
+        case wfShort:
         {
             prec = 8 - offset;
             break;
         }
-        case (wfFree):
-        case (wfLong):
+
+        case wfFree:
+        case wfLong:
         {
             prec = 16 - offset;
             break;
         }
+
         default:
         {
+            FatalErrorInFunction
+                << "Unknown writeFormat enumeration" << abort(FatalError);
         }
     }
 
@@ -96,10 +100,10 @@ void Foam::nastranSurfaceWriter::formatOS(OFstream& os) const
 }
 
 
-void Foam::nastranSurfaceWriter::writeKeyword
+Foam::Ostream& Foam::nastranSurfaceWriter::writeKeyword
 (
-    const word& keyword,
-    Ostream& os
+    Ostream& os,
+    const word& keyword
 ) const
 {
     os.setf(ios_base::left);
@@ -111,11 +115,13 @@ void Foam::nastranSurfaceWriter::writeKeyword
             os  << setw(8) << keyword;
             break;
         }
+
         case wfLong:
         {
             os  << setw(8) << word(keyword + '*');
             break;
         }
+
         case wfFree:
         {
             os  << keyword;
@@ -124,14 +130,16 @@ void Foam::nastranSurfaceWriter::writeKeyword
     }
 
     os.unsetf(ios_base::left);
+
+    return os;
 }
 
 
 void Foam::nastranSurfaceWriter::writeCoord
 (
+    Ostream& os,
     const point& p,
-    const label pointi,
-    OFstream& os
+    const label pointI
 ) const
 {
     // Fixed short/long formats:
@@ -145,21 +153,14 @@ void Foam::nastranSurfaceWriter::writeCoord
     // 8 PS   : single point constraints             (blank)
     // 9 SEID : super-element ID
 
-
-    writeKeyword("GRID", os);
-
-    os  << separator_;
+    writeKeyword(os, "GRID")    << separator_;
 
     os.setf(ios_base::right);
 
-    writeValue(pointi + 1, os);
-    os  << separator_;
-    writeValue("", os);
-    os  << separator_;
-    writeValue(p.x(), os);
-    os  << separator_;
-    writeValue(p.y(), os);
-    os  << separator_;
+    writeValue(os, pointI+1)    << separator_;
+    writeValue(os, "")          << separator_;
+    writeValue(os, p.x())       << separator_;
+    writeValue(os, p.y())       << separator_;
 
     switch (writeFormat_)
     {
@@ -168,27 +169,26 @@ void Foam::nastranSurfaceWriter::writeCoord
             os  << setw(8) << p.z()
                 << nl;
             os.unsetf(ios_base::right);
-
             break;
         }
+
         case wfLong:
         {
             os  << nl;
             os.unsetf(ios_base::right);
-            writeKeyword("", os);
+            writeKeyword(os, "");
             os.setf(ios_base::right);
-            writeValue(p.z(), os);
-            os  << nl;
 
+            writeValue(os, p.z())  << nl;
             break;
         }
+
         case wfFree:
         {
-            writeValue(p.z(), os);
-            os  << nl;
-
+            writeValue(os, p.z())  << nl;
             break;
         }
+
         default:
         {
             FatalErrorInFunction
@@ -202,11 +202,11 @@ void Foam::nastranSurfaceWriter::writeCoord
 
 void Foam::nastranSurfaceWriter::writeFace
 (
+    Ostream& os,
     const word& faceType,
-    const labelList& facePts,
-    label& nFace,
-    const label PID,
-    OFstream& os
+    const labelUList& facePts,
+    const label nFace,
+    const label PID
 ) const
 {
     // Only valid surface elements are CTRIA3 and CQUAD4
@@ -223,15 +223,12 @@ void Foam::nastranSurfaceWriter::writeFace
 
     // For CTRIA3 elements, cols 7 onwards are not used
 
-    writeKeyword(faceType, os);
-    os  << separator_;
+    writeKeyword(os, faceType)   << separator_;
 
     os.setf(ios_base::right);
 
-    writeValue(nFace++, os);
-    os  << separator_;
-
-    writeValue(PID, os);
+    writeValue(os, nFace)        << separator_;
+    writeValue(os, PID);
 
     switch (writeFormat_)
     {
@@ -239,7 +236,7 @@ void Foam::nastranSurfaceWriter::writeFace
         {
             forAll(facePts, i)
             {
-                writeValue(facePts[i] + 1, os);
+                writeValue(os, facePts[i] + 1);
             }
 
             break;
@@ -248,12 +245,12 @@ void Foam::nastranSurfaceWriter::writeFace
         {
             forAll(facePts, i)
             {
-                writeValue(facePts[i] + 1, os);
+                writeValue(os, facePts[i] + 1);
                 if (i == 1)
                 {
                     os  << nl;
                     os.unsetf(ios_base::right);
-                    writeKeyword("", os);
+                    writeKeyword(os, "");
                     os.setf(ios_base::right);
                 }
             }
@@ -265,7 +262,7 @@ void Foam::nastranSurfaceWriter::writeFace
             forAll(facePts, i)
             {
                 os  << separator_;
-                writeValue(facePts[i] + 1, os);
+                writeValue(os, facePts[i] + 1);
             }
 
             break;
@@ -284,9 +281,9 @@ void Foam::nastranSurfaceWriter::writeFace
 
 void Foam::nastranSurfaceWriter::writeGeometry
 (
+    Ostream& os,
     const meshedSurf& surf,
-    List<DynamicList<face>>& decomposedFaces,
-    OFstream& os
+    List<DynamicList<face>>& decomposedFaces
 ) const
 {
     const pointField& points = surf.points();
@@ -301,7 +298,7 @@ void Foam::nastranSurfaceWriter::writeGeometry
 
     forAll(points, pointi)
     {
-        writeCoord(points[pointi], pointi, os);
+        writeCoord(os, points[pointi], pointi);
     }
 
     // Write faces
@@ -312,8 +309,7 @@ void Foam::nastranSurfaceWriter::writeGeometry
         << "$ Faces" << nl
         << "$" << nl;
 
-    label nFace = 1; // the element-id
-
+    label nFace = 0; // the element-id
     forAll(faces, facei)
     {
         const face& f = faces[facei];
@@ -322,12 +318,12 @@ void Foam::nastranSurfaceWriter::writeGeometry
 
         if (f.size() == 3)
         {
-            writeFace("CTRIA3", f, nFace, PID, os);
+            writeFace(os, "CTRIA3", f, ++nFace, PID);
             decomposedFaces[facei].append(f);
         }
         else if (f.size() == 4)
         {
-            writeFace("CQUAD4", f, nFace, PID, os);
+            writeFace(os, "CQUAD4", f, ++nFace, PID);
             decomposedFaces[facei].append(f);
         }
         else
@@ -339,7 +335,7 @@ void Foam::nastranSurfaceWriter::writeGeometry
 
             forAll(triFaces, trii)
             {
-                writeFace("CTRIA3", triFaces[trii], nFace, PID, os);
+                writeFace(os, "CTRIA3", triFaces[trii], ++nFace, PID);
                 decomposedFaces[facei].append(triFaces[trii]);
             }
         }
@@ -347,7 +343,7 @@ void Foam::nastranSurfaceWriter::writeGeometry
 }
 
 
-void Foam::nastranSurfaceWriter::writeFooter
+Foam::Ostream& Foam::nastranSurfaceWriter::writeFooter
 (
     Ostream& os,
     const meshedSurf& surf
@@ -363,15 +359,14 @@ void Foam::nastranSurfaceWriter::writeFooter
 
     for (auto pid : pidsUsed)
     {
-        writeKeyword("PSHELL", os);
-        os  << separator_;
-        writeValue(pid+1, os);  // 1-offset for PID
+        writeKeyword(os, "PSHELL")  << separator_;
+        writeValue(os, pid+1);  // 1-offset for PID
 
-        for (label i = 0; i < 7; i++)
+        for (label i = 0; i < 7; ++i)
         {
             // Dummy values
             os  << separator_;
-            writeValue(1, os);
+            writeValue(os, 1);
         }
         os  << nl;
     }
@@ -381,17 +376,18 @@ void Foam::nastranSurfaceWriter::writeFooter
 
     label MID = 1;
 
-    writeKeyword("MAT1", os);
-    os  << separator_;
-    writeValue(MID, os);
+    writeKeyword(os, "MAT1")    << separator_;
+    writeValue(os, MID);
 
-    for (label i = 0; i < 7; i++)
+    for (label i = 0; i < 7; ++i)
     {
         // Dummy values
         os  << separator_;
-        writeValue("", os);
+        writeValue(os, "");
     }
     os << nl;
+
+    return os;
 }
 
 
@@ -416,7 +412,10 @@ Foam::nastranSurfaceWriter::nastranSurfaceWriter(const dictionary& options)
 {
     if (options.found("format"))
     {
-        writeFormat_ = writeFormatNames_.read(options.lookup("format"));
+        writeFormat_ = writeFormatNames_.read
+        (
+            options.lookup("format")
+        );
     }
 
     if (writeFormat_ == wfFree)
@@ -424,7 +423,7 @@ Foam::nastranSurfaceWriter::nastranSurfaceWriter(const dictionary& options)
         separator_ = ",";
     }
 
-    List<Tuple2<word, word>> fieldSet(options.lookup("fields"));
+    List<Pair<word>> fieldSet(options.lookup("fields"));
 
     forAll(fieldSet, i)
     {
@@ -464,21 +463,16 @@ Foam::fileName Foam::nastranSurfaceWriter::write
         Info<< "Writing nastran file to " << os.name() << endl;
     }
 
-    os  << "TITLE=OpenFOAM " << surfaceName.c_str() << " mesh" << nl
+    os  << "TITLE=OpenFOAM " << surfaceName.c_str()
+        << " mesh" << nl
         << "$" << nl
         << "BEGIN BULK" << nl;
 
     List<DynamicList<face>> decomposedFaces;
-    writeGeometry(surf, decomposedFaces, os);
+    writeGeometry(os, surf, decomposedFaces);
 
-    if (!isDir(outputDir))
-    {
-        mkDir(outputDir);
-    }
-
-    writeFooter(os, surf);
-
-    os  << "ENDDATA" << endl;
+    writeFooter(os, surf)
+        << "ENDDATA" << endl;
 
     return os.name();
 }
diff --git a/src/sampling/sampledSurface/writers/nastran/nastranSurfaceWriter.H b/src/sampling/sampledSurface/writers/nastran/nastranSurfaceWriter.H
index cfee9c3952..921182af98 100644
--- a/src/sampling/sampledSurface/writers/nastran/nastranSurfaceWriter.H
+++ b/src/sampling/sampledSurface/writers/nastran/nastranSurfaceWriter.H
@@ -94,13 +94,13 @@ private:
     // Private data
 
         static const NamedEnum<writeFormat, 3> writeFormatNames_;
-        static const NamedEnum<dataFormat, 2> dataFormatNames_;
+        static const NamedEnum<dataFormat,  2> dataFormatNames_;
 
         //- Write option
         writeFormat writeFormat_;
 
         //- Mapping from field name to data format enumeration
-        HashTable<dataFormat, word> fieldMap_;
+        HashTable<dataFormat> fieldMap_;
 
         //- Scale to apply to values (default = 1.0)
         scalar scale_;
@@ -111,63 +111,60 @@ private:
 
     // Private Member Functions
 
-        //- Initialise the output stream format params
-        void formatOS(OFstream& os) const;
+        //- Initialise the output stream format parameters
+        void formatOS(Ostream& os) const;
 
-        //- Write a co-ordinate
+        //- Write a coordinate
         void writeCoord
         (
+            Ostream& os,
             const point& p,
-            const label pointi,
-            OFstream& os
+            const label pointI  //!< 0-based Point Id
         ) const;
 
         //- Write a face element (CTRIA3 or CQUAD4)
         void writeFace
         (
+            Ostream& os,
             const word& faceType,
-            const labelList& facePts,
-            label& nFace,
-            const label PID,
-            OFstream& os
+            const labelUList& facePts,
+            const label EID,    //!< 1-based Element Id
+            const label PID     //!< 1-based Property Id
         ) const;
 
         //- Main driver to write the surface mesh geometry
         void writeGeometry
         (
+            Ostream& os,
             const meshedSurf& surf,
-            List<DynamicList<face>>& decomposedFaces,
-            OFstream& os
+            List<DynamicList<face>>& decomposedFaces
         ) const;
 
         //- Write the formatted keyword to the output stream
-        void writeKeyword
+        Ostream& writeKeyword
         (
-            const word& keyword,
-            Ostream& os
+            Ostream& os,
+            const word& keyword
         ) const;
 
         //- Write the footer information
-        void writeFooter(Ostream& os, const meshedSurf& surf) const;
+        Ostream& writeFooter(Ostream& os, const meshedSurf& surf) const;
 
         //- Write a formatted value to the output stream
         template<class Type>
-        void writeValue
-        (
-            const Type& value,
-            Ostream& os
-        ) const;
+        Ostream& writeValue(Ostream& os, const Type& value) const;
 
         //- Write a face-based value
         template<class Type>
-        void writeFaceValue
+        Ostream& writeFaceValue
         (
+            Ostream& os,
             const dataFormat& format,
             const Type& value,
-            const label EID,
-            Ostream& os
+            const label EID     //!< 1-based Element Id
         ) const;
 
+
         //- Templated write operation
         template<class Type>
         fileName writeTemplate
diff --git a/src/sampling/sampledSurface/writers/nastran/nastranSurfaceWriterTemplates.C b/src/sampling/sampledSurface/writers/nastran/nastranSurfaceWriterTemplates.C
index 4ee46f5eb0..048088791c 100644
--- a/src/sampling/sampledSurface/writers/nastran/nastranSurfaceWriterTemplates.C
+++ b/src/sampling/sampledSurface/writers/nastran/nastranSurfaceWriterTemplates.C
@@ -30,10 +30,10 @@ License
 // * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
 
 template<class Type>
-void Foam::nastranSurfaceWriter::writeValue
+Foam::Ostream& Foam::nastranSurfaceWriter::writeValue
 (
-    const Type& value,
-    Ostream& os
+    Ostream& os,
+    const Type& value
 ) const
 {
     switch (writeFormat_)
@@ -54,16 +54,18 @@ void Foam::nastranSurfaceWriter::writeValue
             break;
         }
     }
+
+    return os;
 }
 
 
 template<class Type>
-void Foam::nastranSurfaceWriter::writeFaceValue
+Foam::Ostream& Foam::nastranSurfaceWriter::writeFaceValue
 (
+    Ostream& os,
     const dataFormat& format,
     const Type& value,
-    const label EID,
-    Ostream& os
+    const label EID
 ) const
 {
     // Fixed short/long formats supporting PLOAD2 and PLOAD4:
@@ -84,16 +86,13 @@ void Foam::nastranSurfaceWriter::writeFaceValue
 
     Type scaledValue = scale_*value;
 
-    // Write Keyword
-    writeKeyword(dataFormatNames_[format], os);
-
-    os  << separator_;
+    // Write keyword
+    writeKeyword(os, dataFormatNames_[format])  << separator_;
 
     // Write load set ID
     os.setf(ios_base::right);
-    writeValue(SID, os);
 
-    os  << separator_;
+    writeValue(os, SID) << separator_;
 
     switch (format)
     {
@@ -101,7 +100,7 @@ void Foam::nastranSurfaceWriter::writeFaceValue
         {
             if (pTraits<Type>::nComponents == 1)
             {
-                writeValue(scaledValue, os);
+                writeValue(os, scaledValue) << separator_;
             }
             else
             {
@@ -110,22 +109,21 @@ void Foam::nastranSurfaceWriter::writeFaceValue
                     << "and cannot be used for higher rank values"
                     << endl;
 
-                writeValue(scalar(0), os);
+                writeValue(os, scalar(0)) << separator_;
             }
 
-            os  << separator_;
-            writeValue(EID, os);
+            writeValue(os, EID);
             break;
         }
 
         case dfPLOAD4:
         {
-            writeValue(EID, os);
+            writeValue(os, EID);
 
-            for (direction dirI = 0; dirI < pTraits<Type>::nComponents; dirI++)
+            for (direction dirI = 0; dirI < pTraits<Type>::nComponents; ++dirI)
             {
                 os  << separator_;
-                writeValue(component(scaledValue, dirI), os);
+                writeValue(os, component(scaledValue, dirI));
             }
             break;
         }
@@ -141,6 +139,8 @@ void Foam::nastranSurfaceWriter::writeFaceValue
     os.unsetf(ios_base::right);
 
     os << nl;
+
+    return os;
 }
 
 
@@ -185,15 +185,15 @@ Foam::fileName Foam::nastranSurfaceWriter::writeTemplate
         Info<< "Writing nastran file to " << os.name() << endl;
     }
 
-    os  << "TITLE=OpenFOAM " << surfaceName.c_str() << " " << fieldName
-        << " data" << nl
+    os  << "TITLE=OpenFOAM " << surfaceName.c_str()
+        << " " << fieldName << " data" << nl
         << "$" << nl
         << "TIME " << timeValue << nl
         << "$" << nl
         << "BEGIN BULK" << nl;
 
     List<DynamicList<face>> decomposedFaces;
-    writeGeometry(surf, decomposedFaces, os);
+    writeGeometry(os, surf, decomposedFaces);
 
     os  << "$" << nl
         << "$ Field data" << nl
@@ -201,7 +201,7 @@ Foam::fileName Foam::nastranSurfaceWriter::writeTemplate
 
     if (isNodeValues)
     {
-        label n = 0;
+        label elemId = 0;
 
         forAll(decomposedFaces, i)
         {
@@ -217,28 +217,26 @@ Foam::fileName Foam::nastranSurfaceWriter::writeTemplate
                 }
                 v /= f.size();
 
-                writeFaceValue(format, v, ++n, os);
+                writeFaceValue(os, format, v, ++elemId);
             }
         }
     }
     else
     {
-        label n = 0;
+        label elemId = 0;
 
         forAll(decomposedFaces, i)
         {
             const DynamicList<face>& dFaces = decomposedFaces[i];
-
             forAll(dFaces, facei)
             {
-                writeFaceValue(format, values[facei], ++n, os);
+                writeFaceValue(os, format, values[facei], ++elemId);
             }
         }
     }
 
-    writeFooter(os, surf);
-
-    os  << "ENDDATA" << endl;
+    writeFooter(os, surf)
+        << "ENDDATA" << endl;
 
     return os.name();
 }